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