Given two sides of a triangle b = 133, c = 127 and ∠C = 60 °, adjacent to one of them. Find the third side.
| April 11, 2021 | education
We use to solve the cosine theorem for a triangle.
AB ^ 2 = AC ^ 2 + BC ^ 2 – 2 * AC * BC * Cos60.
16129 = 17689 + BC ^ 2 – 2 * 133 * BC * 1/2.
BC ^ 2 – 133 * BC + 1560 = 0.
Having solved the quadratic equation, we get two roots.
BC = 120 cm.
BC = 13 cm.
Answer: The length of the third side can be 13 cm or 120 cm.
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