Question

Find the area of triangle formed by two vectors A=2i+j-2k and B = 3i-j+2k as sides

Answer 1

a=i+2j+3k

b=3i-j+2k

we know that i.i=1 , j.j=1 , k.k=1. and i.j=j.i=i.k=k.i=j.k=k.j=0.

a.b=3-2+6=7

a.b=abcosθ

cosθ=(a.b)÷ab

{a=√a.a, b=√b.b} [ a=√14=b}

cosθ=7÷(14)=.5

θ=60

Hope it helps :)

Answer 2

Doing the scalar product of these two vectors we get vector(say C) which is 0î-10j-5k the magnitude of this vector is the area of triangle which is 5(5)^1/2