4．梁AC 和CD 用铰C 连接，梁的自重不计，试作出梁AD 的整体受力图。（5分）

<img src、"http://sichuan.ouchn.cn/pluginfile.php/56687/question/answer/16784/27/224063/01.png" alt="" width="396" height="163">

<img src、"http://sichuan.ouchn.cn/pluginfile.php/56687/question/answer/16784/27/224064/02.png" alt="" width="414" height="138">

<img src、"http://sichuan.ouchn.cn/pluginfile.php/56687/question/answer/16784/27/224065/03.png" alt="" width="394" height="161">

<img src、"http://sichuan.ouchn.cn/pluginfile.php/56687/question/answer/16784/27/224066/04.png" alt="" width="399" height="150">