The correct option is C right angled triangle
Here,
→b+→c=(^i−3^j+5^k)+(2^i+^j−4^k)
=3^i−2^j+^k
⇒→b+→c=→a
∴→a,→b,→c represent sides of a triangle.
|→a|=√(3)2+(−2)2+(1)2
=√9+4+1
=√14
|→b|=√(1)2+(−3)2+(5)2
=√1+9+25
⇒|→b|=√35
|→c|=√(2)2+(1)2+(−4)2
=√4+1+16
=√21
⇒(√21)2+(√14)2=(√35)2
⇒21+14=35
35=35
⟹|→c|2+|→a|2=|→b|2
By the Pythagoras theorem, triangle formed by →a, →band →c is a right angled triangle