Solve `7cos^2theta+3sin^2theta=4`

Explanation

To solve the equation \( 7\cos^2\theta + 3\sin^2\theta = 4 \), we can follow these steps:

### Step 1: Rewrite the equation using the Pythagorean identity
We know that \( \sin^2\theta + \cos^2\theta = 1 \). We can express \( \sin^2\theta \) in terms of \( \cos^2\theta \):
\[ \sin^2\theta = 1 - \cos^2\theta \]
Substituting this into the original equation gives:
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