=======================
Vertices:
A(-4,-2,0);
B(5,-5,0);
C(3,4,0);
D(1,-1,3).
=======================
Task No: 0 ========================= 
Edges are:
AB=(9,-3,0);
AC=(7,6,0);
AD=(5,1,3).
Squares of lengths of edges are:
|AB|^2=90;
|AC|^2=85;
|AD|^2=35.
Dot product of AB and AC is: 45
Square of cosine: 0.264706
Square of projection of AB on AC: 23.8235
Square of projection of AC on AB: 22.5
Cross product [AB,AC]=(0,0,75).
Square of base ABC:  37.5
Parallelepipedal product: 225
Volume of pyramid: 37.5
Equation of base ABC: (0)x+(0)y+(1)z+(0)=0
Equation of perpendicular :
 | x = (1) + (0)t
<  y = (-1) + (0)t
 | z = (3) + (1)t
Projection of D on base: (1,-1,0)
Vector DD1: (0,0,-3)
Square of module of DD': 9
=======================
Vertices:
A(0,-5,5);
B(0,-5,-5);
C(0,4,-4);
D(-3,-2,-1).
=======================
Task No: 1 ========================= 
Edges are:
AB=(0,0,-10);
AC=(0,9,-9);
AD=(-3,3,-6).
Squares of lengths of edges are:
|AB|^2=100;
|AC|^2=162;
|AD|^2=54.
Dot product of AB and AC is: 90
Square of cosine: 0.5
Square of projection of AB on AC: 50
Square of projection of AC on AB: 81
Cross product [AB,AC]=(90,0,0).
Square of base ABC:  45
Parallelepipedal product: -270
Volume of pyramid: 45
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-3) + (1)t
<  y = (-2) + (0)t
 | z = (-1) + (0)t
Projection of D on base: (0,-2,-1)
Vector DD1: (3,0,0)
Square of module of DD': 9
=======================
Vertices:
A(4,0,-5);
B(5,0,4);
C(-4,0,5);
D(2,1,1).
=======================
Task No: 2 ========================= 
Edges are:
AB=(1,0,9);
AC=(-8,0,10);
AD=(-2,1,6).
Squares of lengths of edges are:
|AB|^2=82;
|AC|^2=164;
|AD|^2=41.
Dot product of AB and AC is: 82
Square of cosine: 0.5
Square of projection of AB on AC: 41
Square of projection of AC on AB: 82
Cross product [AB,AC]=(0,-82,0).
Square of base ABC:  41
Parallelepipedal product: -82
Volume of pyramid: 13.6667
Equation of base ABC: (0)x+(-1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (2) + (0)t
<  y = (1) + (-1)t
 | z = (1) + (0)t
Projection of D on base: (2,0,1)
Vector DD1: (0,-1,0)
Square of module of DD': 1
=======================
Vertices:
A(-5,0,-4);
B(1,0,4);
C(5,0,-5);
D(0,4,-2).
=======================
Task No: 3 ========================= 
Edges are:
AB=(6,0,8);
AC=(10,0,-1);
AD=(5,4,2).
Squares of lengths of edges are:
|AB|^2=100;
|AC|^2=101;
|AD|^2=45.
Dot product of AB and AC is: 52
Square of cosine: 0.267723
Square of projection of AB on AC: 26.7723
Square of projection of AC on AB: 27.04
Cross product [AB,AC]=(0,86,0).
Square of base ABC:  43
Parallelepipedal product: 344
Volume of pyramid: 57.3333
Equation of base ABC: (0)x+(1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (0) + (0)t
<  y = (4) + (1)t
 | z = (-2) + (0)t
Projection of D on base: (0,0,-2)
Vector DD1: (0,-4,0)
Square of module of DD': 16
=======================
Vertices:
A(0,5,-5);
B(0,4,5);
C(0,-5,4);
D(1,1,1).
=======================
Task No: 4 ========================= 
Edges are:
AB=(0,-1,10);
AC=(0,-10,9);
AD=(1,-4,6).
Squares of lengths of edges are:
|AB|^2=101;
|AC|^2=181;
|AD|^2=53.
Dot product of AB and AC is: 100
Square of cosine: 0.547016
Square of projection of AB on AC: 55.2486
Square of projection of AC on AB: 99.0099
Cross product [AB,AC]=(91,0,0).
Square of base ABC:  45.5
Parallelepipedal product: 91
Volume of pyramid: 15.1667
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (1) + (1)t
<  y = (1) + (0)t
 | z = (1) + (0)t
Projection of D on base: (0,1,1)
Vector DD1: (-1,0,0)
Square of module of DD': 1
=======================
Vertices:
A(0,-4,5);
B(0,-4,-4);
C(0,5,2);
D(-3,-1,1).
=======================
Task No: 5 ========================= 
Edges are:
AB=(0,0,-9);
AC=(0,9,-3);
AD=(-3,3,-4).
Squares of lengths of edges are:
|AB|^2=81;
|AC|^2=90;
|AD|^2=34.
Dot product of AB and AC is: 27
Square of cosine: 0.1
Square of projection of AB on AC: 8.1
Square of projection of AC on AB: 9
Cross product [AB,AC]=(81,0,0).
Square of base ABC:  40.5
Parallelepipedal product: -243
Volume of pyramid: 40.5
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-3) + (1)t
<  y = (-1) + (0)t
 | z = (1) + (0)t
Projection of D on base: (0,-1,1)
Vector DD1: (3,0,0)
Square of module of DD': 9
=======================
Vertices:
A(0,-4,3);
B(0,4,-4);
C(0,5,4);
D(-2,2,1).
=======================
Task No: 6 ========================= 
Edges are:
AB=(0,8,-7);
AC=(0,9,1);
AD=(-2,6,-2).
Squares of lengths of edges are:
|AB|^2=113;
|AC|^2=82;
|AD|^2=44.
Dot product of AB and AC is: 65
Square of cosine: 0.455968
Square of projection of AB on AC: 51.5244
Square of projection of AC on AB: 37.3894
Cross product [AB,AC]=(71,0,0).
Square of base ABC:  35.5
Parallelepipedal product: -142
Volume of pyramid: 23.6667
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-2) + (1)t
<  y = (2) + (0)t
 | z = (1) + (0)t
Projection of D on base: (0,2,1)
Vector DD1: (2,0,0)
Square of module of DD': 4
=======================
Vertices:
A(0,3,5);
B(0,5,-5);
C(0,-5,1);
D(-5,1,0).
=======================
Task No: 7 ========================= 
Edges are:
AB=(0,2,-10);
AC=(0,-8,-4);
AD=(-5,-2,-5).
Squares of lengths of edges are:
|AB|^2=104;
|AC|^2=80;
|AD|^2=54.
Dot product of AB and AC is: 24
Square of cosine: 0.0692308
Square of projection of AB on AC: 7.2
Square of projection of AC on AB: 5.53846
Cross product [AB,AC]=(-88,0,0).
Square of base ABC:  44
Parallelepipedal product: 440
Volume of pyramid: 73.3333
Equation of base ABC: (-1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-5) + (-1)t
<  y = (1) + (0)t
 | z = (0) + (0)t
Projection of D on base: (0,1,0)
Vector DD1: (5,0,0)
Square of module of DD': 25
=======================
Vertices:
A(0,0,4);
B(0,4,-4);
C(0,-4,-5);
D(5,0,-2).
=======================
Task No: 8 ========================= 
Edges are:
AB=(0,4,-8);
AC=(0,-4,-9);
AD=(5,0,-6).
Squares of lengths of edges are:
|AB|^2=80;
|AC|^2=97;
|AD|^2=61.
Dot product of AB and AC is: 56
Square of cosine: 0.404124
Square of projection of AB on AC: 32.3299
Square of projection of AC on AB: 39.2
Cross product [AB,AC]=(-68,0,0).
Square of base ABC:  34
Parallelepipedal product: -340
Volume of pyramid: 56.6667
Equation of base ABC: (-1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (5) + (-1)t
<  y = (0) + (0)t
 | z = (-2) + (0)t
Projection of D on base: (0,0,-2)
Vector DD1: (-5,0,0)
Square of module of DD': 25
=======================
Vertices:
A(5,-2,0);
B(-3,-5,0);
C(1,5,0);
D(1,-1,-4).
=======================
Task No: 9 ========================= 
Edges are:
AB=(-8,-3,0);
AC=(-4,7,0);
AD=(-4,1,-4).
Squares of lengths of edges are:
|AB|^2=73;
|AC|^2=65;
|AD|^2=33.
Dot product of AB and AC is: 11
Square of cosine: 0.0255005
Square of projection of AB on AC: 1.86154
Square of projection of AC on AB: 1.65753
Cross product [AB,AC]=(0,0,-68).
Square of base ABC:  34
Parallelepipedal product: 272
Volume of pyramid: 45.3333
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (1) + (0)t
<  y = (-1) + (0)t
 | z = (-4) + (-1)t
Projection of D on base: (1,-1,0)
Vector DD1: (0,0,4)
Square of module of DD': 16
=======================
Vertices:
A(4,3,0);
B(-5,5,0);
C(5,-5,0);
D(1,1,-3).
=======================
Task No: 10 ========================= 
Edges are:
AB=(-9,2,0);
AC=(1,-8,0);
AD=(-3,-2,-3).
Squares of lengths of edges are:
|AB|^2=85;
|AC|^2=65;
|AD|^2=22.
Dot product of AB and AC is: -25
Square of cosine: 0.113122
Square of projection of AB on AC: 9.61539
Square of projection of AC on AB: 7.35294
Cross product [AB,AC]=(0,0,70).
Square of base ABC:  35
Parallelepipedal product: -210
Volume of pyramid: 35
Equation of base ABC: (0)x+(0)y+(1)z+(0)=0
Equation of perpendicular :
 | x = (1) + (0)t
<  y = (1) + (0)t
 | z = (-3) + (1)t
Projection of D on base: (1,1,0)
Vector DD1: (0,0,3)
Square of module of DD': 9
=======================
Vertices:
A(5,0,-5);
B(1,0,5);
C(-5,0,-4);
D(0,-3,-1).
=======================
Task No: 11 ========================= 
Edges are:
AB=(-4,0,10);
AC=(-10,0,1);
AD=(-5,-3,4).
Squares of lengths of edges are:
|AB|^2=116;
|AC|^2=101;
|AD|^2=50.
Dot product of AB and AC is: 50
Square of cosine: 0.213383
Square of projection of AB on AC: 24.7525
Square of projection of AC on AB: 21.5517
Cross product [AB,AC]=(0,-96,0).
Square of base ABC:  48
Parallelepipedal product: 288
Volume of pyramid: 48
Equation of base ABC: (0)x+(-1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (0) + (0)t
<  y = (-3) + (-1)t
 | z = (-1) + (0)t
Projection of D on base: (0,0,-1)
Vector DD1: (0,3,0)
Square of module of DD': 9
=======================
Vertices:
A(0,3,-5);
B(0,4,4);
C(0,-4,0);
D(4,1,0).
=======================
Task No: 12 ========================= 
Edges are:
AB=(0,1,9);
AC=(0,-7,5);
AD=(4,-2,5).
Squares of lengths of edges are:
|AB|^2=82;
|AC|^2=74;
|AD|^2=45.
Dot product of AB and AC is: 38
Square of cosine: 0.23797
Square of projection of AB on AC: 19.5135
Square of projection of AC on AB: 17.6098
Cross product [AB,AC]=(68,0,0).
Square of base ABC:  34
Parallelepipedal product: 272
Volume of pyramid: 45.3333
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (4) + (1)t
<  y = (1) + (0)t
 | z = (0) + (0)t
Projection of D on base: (0,1,0)
Vector DD1: (-4,0,0)
Square of module of DD': 16
=======================
Vertices:
A(0,-1,5);
B(0,5,-5);
C(0,-5,-1);
D(-2,0,0).
=======================
Task No: 13 ========================= 
Edges are:
AB=(0,6,-10);
AC=(0,-4,-6);
AD=(-2,1,-5).
Squares of lengths of edges are:
|AB|^2=136;
|AC|^2=52;
|AD|^2=30.
Dot product of AB and AC is: 36
Square of cosine: 0.183258
Square of projection of AB on AC: 24.9231
Square of projection of AC on AB: 9.52941
Cross product [AB,AC]=(-76,0,0).
Square of base ABC:  38
Parallelepipedal product: 152
Volume of pyramid: 25.3333
Equation of base ABC: (-1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-2) + (-1)t
<  y = (0) + (0)t
 | z = (0) + (0)t
Projection of D on base: (0,0,0)
Vector DD1: (2,0,0)
Square of module of DD': 4
=======================
Vertices:
A(-3,0,-2);
B(5,0,5);
C(5,0,-4);
D(2,-3,0).
=======================
Task No: 14 ========================= 
Edges are:
AB=(8,0,7);
AC=(8,0,-2);
AD=(5,-3,2).
Squares of lengths of edges are:
|AB|^2=113;
|AC|^2=68;
|AD|^2=38.
Dot product of AB and AC is: 50
Square of cosine: 0.325351
Square of projection of AB on AC: 36.7647
Square of projection of AC on AB: 22.1239
Cross product [AB,AC]=(0,72,0).
Square of base ABC:  36
Parallelepipedal product: -216
Volume of pyramid: 36
Equation of base ABC: (0)x+(1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (2) + (0)t
<  y = (-3) + (1)t
 | z = (0) + (0)t
Projection of D on base: (2,0,0)
Vector DD1: (0,3,0)
Square of module of DD': 9
=======================
Vertices:
A(0,-4,5);
B(0,5,-3);
C(0,-4,-4);
D(3,-1,-1).
=======================
Task No: 15 ========================= 
Edges are:
AB=(0,9,-8);
AC=(0,0,-9);
AD=(3,3,-6).
Squares of lengths of edges are:
|AB|^2=145;
|AC|^2=81;
|AD|^2=54.
Dot product of AB and AC is: 72
Square of cosine: 0.441379
Square of projection of AB on AC: 64
Square of projection of AC on AB: 35.7517
Cross product [AB,AC]=(-81,0,0).
Square of base ABC:  40.5
Parallelepipedal product: -243
Volume of pyramid: 40.5
Equation of base ABC: (-1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (3) + (-1)t
<  y = (-1) + (0)t
 | z = (-1) + (0)t
Projection of D on base: (0,-1,-1)
Vector DD1: (-3,0,0)
Square of module of DD': 9
=======================
Vertices:
A(4,0,4);
B(-1,0,-5);
C(-4,0,4);
D(0,2,1).
=======================
Task No: 16 ========================= 
Edges are:
AB=(-5,0,-9);
AC=(-8,0,0);
AD=(-4,2,-3).
Squares of lengths of edges are:
|AB|^2=106;
|AC|^2=64;
|AD|^2=29.
Dot product of AB and AC is: 40
Square of cosine: 0.235849
Square of projection of AB on AC: 25
Square of projection of AC on AB: 15.0943
Cross product [AB,AC]=(0,72,0).
Square of base ABC:  36
Parallelepipedal product: 144
Volume of pyramid: 24
Equation of base ABC: (0)x+(1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (0) + (0)t
<  y = (2) + (1)t
 | z = (1) + (0)t
Projection of D on base: (0,0,1)
Vector DD1: (0,-2,0)
Square of module of DD': 4
=======================
Vertices:
A(-3,-5,0);
B(-4,5,0);
C(4,-2,0);
D(-1,-1,5).
=======================
Task No: 17 ========================= 
Edges are:
AB=(-1,10,0);
AC=(7,3,0);
AD=(2,4,5).
Squares of lengths of edges are:
|AB|^2=101;
|AC|^2=58;
|AD|^2=45.
Dot product of AB and AC is: 23
Square of cosine: 0.0903039
Square of projection of AB on AC: 9.12069
Square of projection of AC on AB: 5.23762
Cross product [AB,AC]=(0,0,-73).
Square of base ABC:  36.5
Parallelepipedal product: -365
Volume of pyramid: 60.8333
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (-1) + (0)t
<  y = (-1) + (0)t
 | z = (5) + (-1)t
Projection of D on base: (-1,-1,0)
Vector DD1: (0,0,-5)
Square of module of DD': 25
=======================
Vertices:
A(0,0,-5);
B(0,-5,5);
C(0,5,5);
D(5,0,2).
=======================
Task No: 18 ========================= 
Edges are:
AB=(0,-5,10);
AC=(0,5,10);
AD=(5,0,7).
Squares of lengths of edges are:
|AB|^2=125;
|AC|^2=125;
|AD|^2=74.
Dot product of AB and AC is: 75
Square of cosine: 0.36
Square of projection of AB on AC: 45
Square of projection of AC on AB: 45
Cross product [AB,AC]=(-100,0,0).
Square of base ABC:  50
Parallelepipedal product: -500
Volume of pyramid: 83.3333
Equation of base ABC: (-1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (5) + (-1)t
<  y = (0) + (0)t
 | z = (2) + (0)t
Projection of D on base: (0,0,2)
Vector DD1: (-5,0,0)
Square of module of DD': 25
=======================
Vertices:
A(-4,-4,0);
B(-1,5,0);
C(5,-1,0);
D(0,0,-1).
=======================
Task No: 19 ========================= 
Edges are:
AB=(3,9,0);
AC=(9,3,0);
AD=(4,4,-1).
Squares of lengths of edges are:
|AB|^2=90;
|AC|^2=90;
|AD|^2=33.
Dot product of AB and AC is: 54
Square of cosine: 0.36
Square of projection of AB on AC: 32.4
Square of projection of AC on AB: 32.4
Cross product [AB,AC]=(0,0,-72).
Square of base ABC:  36
Parallelepipedal product: 72
Volume of pyramid: 12
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (0) + (0)t
<  y = (0) + (0)t
 | z = (-1) + (-1)t
Projection of D on base: (0,0,0)
Vector DD1: (0,0,1)
Square of module of DD': 1
=======================
Vertices:
A(-4,0,-3);
B(-4,0,5);
C(5,0,5);
D(-1,-1,2).
=======================
Task No: 20 ========================= 
Edges are:
AB=(0,0,8);
AC=(9,0,8);
AD=(3,-1,5).
Squares of lengths of edges are:
|AB|^2=64;
|AC|^2=145;
|AD|^2=35.
Dot product of AB and AC is: 64
Square of cosine: 0.441379
Square of projection of AB on AC: 28.2483
Square of projection of AC on AB: 64
Cross product [AB,AC]=(0,72,0).
Square of base ABC:  36
Parallelepipedal product: -72
Volume of pyramid: 12
Equation of base ABC: (0)x+(1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-1) + (0)t
<  y = (-1) + (1)t
 | z = (2) + (0)t
Projection of D on base: (-1,0,2)
Vector DD1: (0,1,0)
Square of module of DD': 1
=======================
Vertices:
A(4,-4,0);
B(-4,-5,0);
C(-3,4,0);
D(-1,-2,-3).
=======================
Task No: 21 ========================= 
Edges are:
AB=(-8,-1,0);
AC=(-7,8,0);
AD=(-5,2,-3).
Squares of lengths of edges are:
|AB|^2=65;
|AC|^2=113;
|AD|^2=38.
Dot product of AB and AC is: 48
Square of cosine: 0.313683
Square of projection of AB on AC: 20.3894
Square of projection of AC on AB: 35.4462
Cross product [AB,AC]=(0,0,-71).
Square of base ABC:  35.5
Parallelepipedal product: 213
Volume of pyramid: 35.5
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (-1) + (0)t
<  y = (-2) + (0)t
 | z = (-3) + (-1)t
Projection of D on base: (-1,-2,0)
Vector DD1: (0,0,3)
Square of module of DD': 9
=======================
Vertices:
A(-4,2,0);
B(5,5,0);
C(5,-5,0);
D(2,1,4).
=======================
Task No: 22 ========================= 
Edges are:
AB=(9,3,0);
AC=(9,-7,0);
AD=(6,-1,4).
Squares of lengths of edges are:
|AB|^2=90;
|AC|^2=130;
|AD|^2=53.
Dot product of AB and AC is: 60
Square of cosine: 0.307692
Square of projection of AB on AC: 27.6923
Square of projection of AC on AB: 40
Cross product [AB,AC]=(0,0,-90).
Square of base ABC:  45
Parallelepipedal product: -360
Volume of pyramid: 60
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (2) + (0)t
<  y = (1) + (0)t
 | z = (4) + (-1)t
Projection of D on base: (2,1,0)
Vector DD1: (0,0,-4)
Square of module of DD': 16
=======================
Vertices:
A(-5,-3,0);
B(3,5,0);
C(3,-4,0);
D(0,-1,1).
=======================
Task No: 23 ========================= 
Edges are:
AB=(8,8,0);
AC=(8,-1,0);
AD=(5,2,1).
Squares of lengths of edges are:
|AB|^2=128;
|AC|^2=65;
|AD|^2=30.
Dot product of AB and AC is: 56
Square of cosine: 0.376923
Square of projection of AB on AC: 48.2462
Square of projection of AC on AB: 24.5
Cross product [AB,AC]=(0,0,-72).
Square of base ABC:  36
Parallelepipedal product: -72
Volume of pyramid: 12
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (0) + (0)t
<  y = (-1) + (0)t
 | z = (1) + (-1)t
Projection of D on base: (0,-1,0)
Vector DD1: (0,0,-1)
Square of module of DD': 1
=======================
Vertices:
A(0,-2,-5);
B(0,5,0);
C(0,-5,3);
D(-1,-1,-1).
=======================
Task No: 24 ========================= 
Edges are:
AB=(0,7,5);
AC=(0,-3,8);
AD=(-1,1,4).
Squares of lengths of edges are:
|AB|^2=74;
|AC|^2=73;
|AD|^2=18.
Dot product of AB and AC is: 19
Square of cosine: 0.0668271
Square of projection of AB on AC: 4.94521
Square of projection of AC on AB: 4.87838
Cross product [AB,AC]=(71,0,0).
Square of base ABC:  35.5
Parallelepipedal product: -71
Volume of pyramid: 11.8333
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-1) + (1)t
<  y = (-1) + (0)t
 | z = (-1) + (0)t
Projection of D on base: (0,-1,-1)
Vector DD1: (1,0,0)
Square of module of DD': 1
=======================
Vertices:
A(4,-1,0);
B(-3,-5,0);
C(-4,5,0);
D(-1,0,2).
=======================
Task No: 25 ========================= 
Edges are:
AB=(-7,-4,0);
AC=(-8,6,0);
AD=(-5,1,2).
Squares of lengths of edges are:
|AB|^2=65;
|AC|^2=100;
|AD|^2=30.
Dot product of AB and AC is: 32
Square of cosine: 0.157538
Square of projection of AB on AC: 10.24
Square of projection of AC on AB: 15.7538
Cross product [AB,AC]=(0,0,-74).
Square of base ABC:  37
Parallelepipedal product: -148
Volume of pyramid: 24.6667
Equation of base ABC: (0)x+(0)y+(-1)z+(0)=0
Equation of perpendicular :
 | x = (-1) + (0)t
<  y = (0) + (0)t
 | z = (2) + (-1)t
Projection of D on base: (-1,0,0)
Vector DD1: (0,0,-2)
Square of module of DD': 4
=======================
Vertices:
A(0,4,0);
B(0,-3,5);
C(0,-3,-5);
D(-4,-1,0).
=======================
Task No: 26 ========================= 
Edges are:
AB=(0,-7,5);
AC=(0,-7,-5);
AD=(-4,-5,0).
Squares of lengths of edges are:
|AB|^2=74;
|AC|^2=74;
|AD|^2=41.
Dot product of AB and AC is: 24
Square of cosine: 0.105186
Square of projection of AB on AC: 7.78378
Square of projection of AC on AB: 7.78378
Cross product [AB,AC]=(70,0,0).
Square of base ABC:  35
Parallelepipedal product: -280
Volume of pyramid: 46.6667
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (-4) + (1)t
<  y = (-1) + (0)t
 | z = (0) + (0)t
Projection of D on base: (0,-1,0)
Vector DD1: (4,0,0)
Square of module of DD': 16
=======================
Vertices:
A(5,0,5);
B(-4,0,5);
C(5,0,-4);
D(2,3,2).
=======================
Task No: 27 ========================= 
Edges are:
AB=(-9,0,0);
AC=(0,0,-9);
AD=(-3,3,-3).
Squares of lengths of edges are:
|AB|^2=81;
|AC|^2=81;
|AD|^2=27.
Dot product of AB and AC is: 0
Square of cosine: 0
Square of projection of AB on AC: 0
Square of projection of AC on AB: 0
Cross product [AB,AC]=(0,-81,0).
Square of base ABC:  40.5
Parallelepipedal product: -243
Volume of pyramid: 40.5
Equation of base ABC: (0)x+(-1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (2) + (0)t
<  y = (3) + (-1)t
 | z = (2) + (0)t
Projection of D on base: (2,0,2)
Vector DD1: (0,-3,0)
Square of module of DD': 9
=======================
Vertices:
A(3,0,4);
B(-4,0,-4);
C(5,0,-4);
D(1,-4,-1).
=======================
Task No: 28 ========================= 
Edges are:
AB=(-7,0,-8);
AC=(2,0,-8);
AD=(-2,-4,-5).
Squares of lengths of edges are:
|AB|^2=113;
|AC|^2=68;
|AD|^2=45.
Dot product of AB and AC is: 50
Square of cosine: 0.325351
Square of projection of AB on AC: 36.7647
Square of projection of AC on AB: 22.1239
Cross product [AB,AC]=(0,-72,0).
Square of base ABC:  36
Parallelepipedal product: 288
Volume of pyramid: 48
Equation of base ABC: (0)x+(-1)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (1) + (0)t
<  y = (-4) + (-1)t
 | z = (-1) + (0)t
Projection of D on base: (1,0,-1)
Vector DD1: (0,4,0)
Square of module of DD': 16
=======================
Vertices:
A(0,2,4);
B(0,-5,5);
C(0,-3,-5);
D(2,-2,1).
=======================
Task No: 29 ========================= 
Edges are:
AB=(0,-7,1);
AC=(0,-5,-9);
AD=(2,-4,-3).
Squares of lengths of edges are:
|AB|^2=50;
|AC|^2=106;
|AD|^2=29.
Dot product of AB and AC is: 26
Square of cosine: 0.127547
Square of projection of AB on AC: 6.37736
Square of projection of AC on AB: 13.52
Cross product [AB,AC]=(68,0,0).
Square of base ABC:  34
Parallelepipedal product: 136
Volume of pyramid: 22.6667
Equation of base ABC: (1)x+(0)y+(0)z+(0)=0
Equation of perpendicular :
 | x = (2) + (1)t
<  y = (-2) + (0)t
 | z = (1) + (0)t
Projection of D on base: (0,-2,1)
Vector DD1: (-2,0,0)
Square of module of DD': 4
