## Trigonometry (11th Edition) Clone

$\cos(-8.0142^\circ)$ is the answer to this exercise.
$$\sin98.0142^\circ$$ As cosine and sine are cofunctions, $\cos\theta$ is the cofunction needed to find as long as $\theta$ satisfies $$\cos\theta=\sin98.0142^\circ\hspace{1cm}(1)$$ According to Cofunction Identity: $\tan\theta=\cot(90^\circ-\theta)$ Apply this to the equation $(1)$: $$\sin(90^\circ-\theta)=\sin98.0142^\circ$$ $$90^\circ-\theta=98.0142^\circ$$ $$\theta=90^\circ-98.0142^\circ=-8.0142^\circ$$ Hence, $\cos(-8.0142^\circ)$ is the answer to this exercise.