The horizontal range and the maximum height of a projectile

The horizontal range and the maximum height of a projectile are equal. The angle of projection of the projectiles is :

Horizontal range =	u² sin 2θ	.....(1)
	g

Maximum height =	u² sin² θ	.....(2)
	2g

According to the problem
R = H

	u² sin 2θ	=	u² sin² θ
	g		2g

⇒ 2 sin θ cos θ =	sin² θ
	2

2 cos θ =	sin θ
	2

⇒ cot θ =	1
	4

⇒ tan θ = 4
⇒ θ = [ tan^-1 (4) ]