수직축 정리

$$\title{Perpendicular Axis Theorem}$$ $$ \begin{aligned} I_z &=\int r^2\dd m\\ &=\int \br{x^2+y^2}\dd m\\ &=\int {x^2}\dd m+\int {y^2}\dd m\\ &=I_x+I_y\\ \end{aligned} $$