Find the value of `cos15^(@)` with the help of `cos 2A=2cos^(2)A-1`

Explanation

To find the value of \( \cos 15^\circ \) using the identity \( \cos 2A = 2 \cos^2 A - 1 \), we can follow these steps:

### Step 1: Identify the angle
Let \( A = 15^\circ \). Therefore, \( 2A = 30^\circ \).

### Step 2: Apply the cosine double angle formula
Using the formula \( \cos 2A = 2 \cos^2 A - 1 \), we can write:
\[
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