Question

A ball is thrown upwards at an angle of 60 degree to the horizontal . It falls on the ground at a distance of 90m if the ball is thrown with the same initial velocity at an angle of 30 degree it will fall on the ground at a distance of

Answer 1

60° and 30° are complementary angles. For complementary angles range is same. Hence it will fall on the ground at a distances of 90m

Proof:
R = u^2 Sin(2θ)/g

R ∝ Sin(2θ)

R₁/R₂ = Sin(2θ₁)/Sin(2θ₂)
R₂ = R₁ * Sin(2θ₂)/Sin(2θ₁)
R₂ = 90 * Sin(2*30) / Sin(2*60)
R₂ = 90 * Sin60/Sin120
R₂ = 90 * 1 >>>>>>[ As value of Sin60 and Sin120 is same]
R₂ = 90m