A triangle has sides 5 cm, 8 cm and 7 cm. What is the angle between the sides of 5 cm and 8 cm?
Answer and explanation
Correct answer: D. 60°
- Step 1: By the cosine law, c² = a² + b² - 2ab cos C.
- Step 2: cos C = (25 + 64 - 49) / (2 x 5 x 8) = 1/2, so C = 60°.
Answer
60°.
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