## Trigonometry (11th Edition) Clone

$$\sin35^\circ=\cos55^\circ$$ 18 is matched with B.
$$\sin35^\circ$$ We know that $35^\circ+55^\circ=90^\circ$. Now remind yourself of Cofunction Identity for sines and cosines, which state $$\sin\theta=\cos(90^\circ-\theta)$$ Thus, $$\sin35^\circ=\cos(90^\circ-35^\circ)=\cos55^\circ$$ $\cos55^\circ$ is choice B. 18 is matched with B.