A projectile is projected with a speed `u` at an angle `theta` with the horizontal. What is the speed when its direction of motion makes an angle `theta//2` with the horizontal

Options

A. `(ucos 2theta)//2`
B. `u cos theta`
C. `u(2 cos theta - sec theta)`
D. `u(cos theta - sec theta)`

Answer

C

Explanation

`v cos theta = u cos 2theta`
`v = (u(2 cos^(2) theta -1)/(cos theta)) = u[2cos theta - sec theta]`