1. 如圖所示桁架結構在 C 點施加一水平力 20 kN。A、B 為鉸支承，整體結構可視為二子桁架在 E 點鉸接。請分析各反力與桿件 DE、EF 之內力為何？(25 分)

2. A pressurized cylindrical tank with flat ends is loaded by torques T and tensile forces P as shown in Fig. 2. The tank has inner radius of r = 125 mm and wall thickness t = 6.5 mm. The internal pressure p = 7.25 MPa and the torque T = 850 N-m. What is the maximum permissible value of the forces P if the allowable tensile stress in the wall of the cylinder is 80 MPa? (20%)Fig. 2