Question

what is maximum height of projectile when horizantal range is maximum?

Answer 1

Horizontal range is maximum when θ = 45°
R = u^2 Sin(2θ) / g
= u^2 / g

Maximum height = (u^2 Sin^2 θ) / (2g)
= u^2 / (4g)
= R / 4

Maximum height of projectile is R/4