고체역학 (Gere) — Tension, Compression, and Shear: Problem 1.3-11

1.3-11 Repeat 1.3-9 but use the method of sections to find member forces in AC and BD. Reference Problem 1.3-9: Find support reactions at A and B and then use the method of joints to find all member forces. Let \( c = 2.5 \text{ m} \) and \( P = 90 \text{ kN} \).