Two objects are projected at an angle $$\theta^{\circ}$$ and $$\left(90-\theta^{\circ}\right)$$, to the horizontal with the same speed. The ratio of their maximum vertical heights is

The maximum range of a gun on horizontal plane is $$16 \mathrm{~km}$$. If $$\mathrm{g}=10 \mathrm{~ms}^{-2}$$, then muzzle velocity of a shell is

The trajectory of projectile is

For a projectile motion, the angle between the velocity and acceleration is minimum and acute at