Find the Exact Value cos(180 degrees )^2-sin(180 degrees )^2

$\cos^{2} (180 °) - \sin^{2} (180 °)$

Apply the cosine double-angle identity.

$\cos (2 \cdot 180 °)$

Multiply $2$ by $180 °$ .

$\cos (360)$

Remove full rotations of $360$ ° until the angle is between $0$ ° and $360$ °.

$\cos (0)$

The exact value of $\cos (0)$ is $1$ .

$1$

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