If `vecA+ vecB = vecC and A+B+C=0`, then the angle between `vecA and vecB` is :

Options

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

Answer

1

Explanation

`vecA+ vecB= vecC rArr sqrt (A^(2) + B^(2) + 2AB cos theta)= C`
and `A+B = C rArr sqrt(A^(2)+ B^(2) + 2AB cos theta) =A+B`
`rArr A^(2) + B^(2) + 2AB cos theta = A^(2) + B^(2) + 2AB`
`rArr cos theta = 1 rArr theta =0^(@)`