AP EAMCET Engineering 21 Apr 2019 Shift 2 Paper

The mid points of the sides are given as,
AB,BC and CA are (3,0,0),(0,4,0),(0,0,5)
The coordinates of A,B and C
A=(3,−4,5)
B=(3,4,−5)
C=(−3,4,5)
And
AB2‌‌=(x2−x1)2+(y2−y1)2+(z2−z1)2
‌‌=(3−3)2+(4+4)2+(−5−5)2
‌‌=82+102
‌‌=164
Similarly,
BC2=(−3−3)2+(4−4)2+(5+5)2
=36+100
=136
Similarly,
CA2‌‌=(−3−3)2+(4−4)2+(5+5)2
‌‌=36+64
‌‌=100
AB2+BC2+CD2‌‌=164+136+100
‌‌=400