# Perpendicular axis theorem ( at moments of inertia)

## Description

Perpendicular axis theorem (or plane figure theorem) can be used to determine the moment of inertia of a rigid object that lies entirely within a plane, about an axis perpendicular to the plane, given the moments of inertia of the object about two perpendicular axes lying within the plane. The axes must all pass through a single point in the plane.

If a body lies in the xy plane and the z axis is perpendicular to the plane of the body, then the moment of inertia about the z axis is the sum of the moments of inertia at the x and y axes.

## Variables

I_{z} | Moment of inertia (Perpendicular axis ) (kg*m^{2}) |

I_{x} | Moment of inertia ( axis x) (kg*m^{2}) |

I_{y} | Moment of inertia ( axis y) (kg*m^{2}) |