The sides of the triangle are 14, 10 and 6 cm. Find the angle opposite the 14 cm side.
| September 24, 2021 | education
In a triangle ABC AB = 14; BC = 10; AC = 6; angle C lies opposite side AB;
By the cosine theorem:
AB² = AC² + BC² – 2 * AC * BC * cos C;
cos C = (AC² + BC² – AB²): (2 * AC * BC) = (6² + 10² – 14²): (2 * 6 * 10) =
= (36 + 100 – 196): 120 = – 0.5;
<C = 120 °.
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