The equivalent length of a simple pendulum which gives the same frequency as compound pendulum is

The path of the projectile is a parabola.

The angle between two forces when the resultant is maximum and minimum respectively are

The triangle law of forces states that if two forces acting simultaneously on a particle, be represented in magnitude and direction by the two sides of a triangle taken in order, then their resultant may be represented in magnitude and direction by the third side of a triangle, taken in opposite order.

The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is known as