Question

What is the angle of projection for a body for maximum horizontal range in angle?

Answer 1

It is 45° or π/4 radian.

In range's formula, you have sin2Φ on numerator.

For range to be max, sin2Φ should be max.

then 2Φ = 90° or π/2 radian.

then Φ= 45° or π/4 radian.