The angle of reflection is the angle the to the reflecting surface.
reflected rays make with a perpendicular line
instant raise makes with a perpendicular line
instant ray makes with a parallel line
reflected ray mix with a parallel line

The two required components for a generator

True or false graphs must include scales that increase by the same amount

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.