4. 一斷面如圖所示，求(a) 5% 通過坐標軸的一次矩 Qx , Qy , 形心 C ，(b) 10% 通過坐標軸二次矩(慣性矩) I x , I y , 慣性積 , (c) 10% 畫出莫爾圓，並求出主軸慣性矩。(25%)

5.如圖三所示(Figure3) Determineθand the tension in the spring, which correspond to the equilibrium position of the spring. The unstretched length of spring is h and the constant of the spring is k. The pin and roller supporters are at A and C, respectively. The point load P works on B with the downward direction and neglect the weight of all objects. (20%)