The range of a projectile when launched at an angle θ is same as when launched at an angle 2θ. What isthe value of θ?

Range of projectile launched at an angle θ is same as the range of projectile launched at angle 2θ.⇒  u2sin2(2θ)g=u2sin2θg⇒ sin2(2θ) = sin2θ⇒ 2 sin 2θ cos 2θ = 2 sinθ cos θ     4 sin θ cos θ cos 28 = 2 sin θ cos θ⇒  4cos2θ=2⇒cos2θ=12⇒ cos 2θ = cos 600 ⇒ 2θ  = 600 ∴        θ = 300