In triangle ABC C=51 degrees, A=39 degreees, AC=27 units . Find BC.

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

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To find the length of the side BC, we'll apply the law of sines. Since BC is the opposite to the angle A, we'll get:

BC/sin A = AC/ sin B

We'll determine the measure of the angle B, based on fact that the sum of the angles in a triangle is 180 degrees.

A + B + C = 180

39 + B + 51 = 180

B = 180 - 39 - 51

B= 90 degrees

BC/sin 39 = 27/ sin 90

BC/sin 39 = 27/ 1

BC/sin 39 = 27

BC = 27*sin 39

BC = 27*0.6293

BC = 17 units approx.

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