What is the angles madeby the trajectory of a projectile with horizontal at maximum height ?

A body is projected with velocity 24 ms^(-1) making an angle 30° with the horizontal. The angle made by the direction of the projectile with the horizontal at 2s from start is

What should be the angle of projection with horizontal for a body to attain maximum height for a given velocity of projection?

Show that the trajectory of an object throw horizontally from certain height is a parabola.

Mention the direction of motion of the projectile at the point of its maximum height .