An particle is projected with velocity `u` on an inclined plane at an angle `theta` with the plane. If the particle lands on the plane at right Angle and its time of flight is `(u cosec theta)/(2 g)`. Find the angle of inclination of the plane with horizontal.

Explanation

`v_x = u_x _ a_x t`
`0 = u cos theta + (-g sin prop) T`
`T = (u cos theta)/(g sin prop) = (u cosec theta)/(2 g)`
`(cos theta)/(sin prop) = (1)/(2 sin theta)`
or `prop = 2 theta`.
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