Geometry

Question Analysis

We aim to find the measure of in using the Law of Cosines, given the lengths of all three sides: , , .

 

Key Concept Explanation

The Law of Cosines states that for a triangle with sides , ,  and the angle  opposite side , . Rearranging this formula to find an angle gives . For , to find , we use , as we know the side lengths and want the angle opposite side .

 

Step - by - Step Solution

1. Identify values: Let , , .

2. Calculate:

First, find the squares:

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