Question

If `vec(A)=vec(B)+vec(C )`, and the magnitudes of `vec(A)`,`vec(B)`,`vec(C )` are 5,4, and 3 units, then the angle between `vec(A)` and `vec(C )` is
A. `sin^(-1)(3//4)`
B. `cos^(-1)(4//5)`
C. `cos^(-1)(3//5)`
D. `pi//2`

Answer 1

Correct Answer - C

`vec(A)=vec(B)+vec(C)`
`cos alpha =(3)/(5) " " rArr " " alpha =53^(@)`
`alpha = cos^(-1)((3)/(5))`