1. A gun is mounted on a hill of height ( h ) above a level plain. Assuming that the path of the projectile is a parabola, find the angle of elevation ( alpha ) for greatest horizontal range and given muzzle speed ( V ).[operatorname{cosec}^{2} alpha=2left(1+frac{g h}{V^{2}}right)]What physical effects are neglected in the above approximation?2. With the same assumptions as in Exercise 1, show that if a projectile is thrown over a double inclined plane from one end of the horizontal base to the other and if it just graves the surmit in its flight, its angle of projection is[tan ^{-1}(tan theta+tan phi)]whero ( theta, phi ) are the slopes of the faces and the motion is in a vertiesl plane through the line of greaiest slope.