In △ ABC, a = 7, B = 43, C = 13, then the minimum angle is () A. π3B. π6C. π4D. π12

In △ ABC, a = 7, B = 43, C = 13, then the minimum angle is () A. π3B. π6C. π4D. π12

∵ in △ ABC, a = 7, B = 43, C = 13, C is the smallest edge, C is the smallest angle. According to cosine theorem, COSC = A2 + B2 − c22ab = 49 + 48 − 132 × 7 × 43 = 32 ∵ C is the inner angle of triangle, C ∈ (0, π), C = π 6, that is, the smallest angle of △ ABC is π 6