‌‌ ⇒ points are ‌P(4,1,3),Q(6,−2,−3)‌ and ‌R(1,−1,−3) ‌⇒PQ=√(6−4)2+(−3)2+(−6)2 ‌=√4+9+36=√49=7 ‌⇒QR=√(1−6)2+(−1+2)2+(−3+3)2 ‌=√(−5)2+(1)2+0=√26 ‌⇒PR=√(1−4)2+(−1−1)2+(−3−3)2 ‌=√9+4+36=√49=7 ‌⇒PQ=PR=7‌ units ‌ ‌⇒△PQR‌ is an isosceles triangle. ‌
