<p>如图所示圆截面直径为d，则截面对O点的极惯性矩为: <img alt="" src="https://file.gaojiufeng.cn/learnAppQuestion/11/5e/115e64491afcb11e476e196df8b82392.jpg" style="width: 100%;height: auto;"><img alt="" src="https://file.gaojiufeng.cn/learnAppQuestion/11/87/118799a5b1dabf910dc5c474cbc851a5.jpg" style="width: 100%;height: auto;"></p>