1) Xc = (Xa+Xb)/2, Xb= 2Xc-Xa = 2*3-(-3) = 9
Yc = (Ya+Yb)/2, Yb = 2Yc-Ya= 2*(-2)-4 = -8
Zc = (Za+Zb)/2, Zb = 2Zc-Za = 2*4-2 = 6
b(9,-8,6)
2) У параллелограмма: AB=CD
AB=(-1-4, 2-(-3), 4-0) = (-5, 5,4)
CD = (2-x, -1-y, -4-z)
2-x=-5
x=7
-1-y=5
y=-6
-4-z=4
z=-8