Geometry

Question Analysis  

The main focus is leveraging the relationship between sine and cosine of complementary angles to re - express in terms of cosine.

Key Concept Explanation  

Complementary Angles: In trigonometry, two angles and are complementary if . The co - function identities state that and .

Step-by-Step Solution  

1. Determine the complementary angle:

Find the angle that, when added to , equals . We calculate .

2. Apply the co - function identity:

Using the identity

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