A magnitude of vector `vecA,vecB` and `vecC` are respectively `12, 5` and `13` units and `vecA+vecB=vecC` then the angle between `vecA` and `vecB` is

Options

A. 0
B. `pi`
C. `pi//2`
D. `pi//4`

Answer

C

Explanation

`|vecA + vecB|=|vecC|`
`sqrt(A^(2) + B^(2) + 2AB cos theta)= sqrt(13^(2))`
`12^(2) + 5^(2) + 2xx 12 xx 5 cos theta = 13^(2)`
`2 xx 12 xx 5 cos theta = 169 - 169 =0`
`" "cos theta= 0`
`" "theta =(pi)/(2)`