If the horizontal range of a projectile is four times its

If the horizontal range of a projectile is four times its maximum height, the angle of projection is

Equation of projectile :

y = x tanθ -	gx³
	2u²cos²θ

	u²sin²θ	= 4×	u²sin²θ
	g		2g

2sinθcosθ = 2sin²θ
tanθ = 1
θ = 45°

sin^-1		1
		4

tan^-1		1
		4