Geometry

Question Analysis

The main focus of this question is to find the cosine of  in a right - triangle. It requires understanding the definition of cosine and correctly identifying the adjacent side and the hypotenuse relative to .

 

Key Concept Explanation

In a right - triangle, the cosine of an acute angle  is defined as . The adjacent side is the side that is next to the angle  (excluding the hypotenuse), and the hypotenuse is the longest side of the right - triangle.

 

Step - by - Step Solution

1. Find the length of the hypotenuse :

Using the Pythagorean theorem , where  () and  (). Then .

2. Identify the sides relative to :

The side adjacent to  is , and the hypotenuse is .

3. Calculate

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