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In the triangle ABC, A.B.C is the three sides opposite to the angle A.B.C, a square - (B-C) square = BC, 1. Find the angle A 2. If BC = 2 times root sign 3, angle B is equal to X and perimeter is y, find the value range of function y = f (x)
A square - (B-C) square = BCA ^ 2-B ^ 2 + 2bc-c ^ 2 = BCA ^ 2 = B ^ 2 + C ^ 2-bc cosine theorem: cosa = (b ^ 2 + C ^ 2-A ^ 2) / (2BC) = BC / (2BC) = 1 / 2, so. A = π / 3 according to sine theorem, B / SINB = A / Sina, a = 2 √ 3, a = π / 3, B = x, B = 4sinx, C / sinc = A / Sina, C = 2 √ 3 / (√ 3 / 2) * sinc = 4Si
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