Question

Find the measure of each indicated side. Round your answer to the nearest tenth.

Answer 1

• m∠R = 78.9°

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We are given three sides and need to find one of angles.

Use the law of cosines:

`cos(A) = \cfrac{ b^2 + c^2 - a^2}{2bc}`

Here we are given:

• R - angle A, a = 59.7, b = 52, c = 41

Substitute above values into the given equation:

`cos(R) = \cfrac{ 52^2 + 41^2 - 59.7^2}{2*52*41} =0.1925`

Find m∠R:

• m∠R = arccos (0.1925), use calculator
• m∠R = 78.9° (rounded to the nearest tenth)