The lengths of the sides of the triangle are 2√3, 9, 7√3. Find the degree measure of the larger angle of the triangle.
| June 24, 2021 | education
Obviously, the larger angle lies opposite the larger side, by the cosine theorem, we get:
(2√3) ^ 2 + 9 ^ 2 – 2 * 2 √3 * 9 cos (a) = (7√3) ^ 2;
18 + 81 – 38√3 cos (a) = 147;
– 38√3 cos (a) = 48;
cos (a) = – 48 / 38√3;
a = arccos (-48 / 38√3).
Answer: the desired angle is arccos (-48 / 38√3).
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