In triangle ABC, ∠A = 60°, BC = 7 cm and AB + AC = 13 cm. What is the area of the triangle?

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Accepted Answer

10√3 cm². Let AB = c and AC = b. Cosine rule: 49 = b^2 + c^2 - bc = (b + c)^2 - 3bc = 169 - 3bc, so bc = 40. Area = 1/2bc 60° = 1/2 × 40 × √32 = 10√3 cm². (The sides are 5 and 8.)

In triangle ABC, ∠A = 60°, BC = 7 cm and AB + AC = 13 cm. What is the area of the triangle?

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