In Projectile
* A path, traced by a projectile in the space, is known as trajectory.
* The velocity with which a projectile is projected, is known as the velocity of projection.
* The angle, with the horizontal, at which a projectile is projected is known as angle of projection.

Angle of projection: Angle of projection is the angle, with the horizontal,at which the projectile is projected.
The range of projectile is maximum, when the angle of projection is 45 degree.

The time of flight of a projectile on downward inclined plane depends upon angle of projection and angle of inclination of the plane.