三角形惯性矩公式推导

截面惯性矩

截面惯性矩（I=面积X面内轴二次）

截面惯性矩：the area moment of inertia

characterized an object's ability to resist bending and is required to calculate displacement.

截面各微元面积与各微元至截面某一指定轴线距离二次方乘积的积分Ix＝ y↑2dF。

截面极惯性矩

截面极惯性矩（Ip=面积X垂直轴二次）。

扭转惯性矩Ip: the torsional moment of inertia

极惯性矩：the polar moment of inertia

截面各微元面积与各微元至垂直于截面的某一指定轴线二次方乘积的积分Ip＝ P↑2dF。

a quantity to predict an object's ability to resist torsion, to calculate the angular displacement of an object subjected to a torque.