An acute angle $\alpha$ has $\cos\alpha=\dfrac5{13}$. Let $\beta=180^\circ-\alpha$.

Question

An acute angle $\alpha$ has $\cos\alpha=\dfrac5{13}$. Let $\beta=180^\circ-\alpha$. Find the exact value of $\sin\alpha$.[2] State the exact values of $\sin\beta$, $\cos\beta$ and $\tan\beta$.[3]

Accepted Answer

(a) $\dfrac{12}{13}$ (b) $\dfrac{12}{13},\ -\dfrac5{13},\ -\dfrac{12}{5}$

Supplementary-angle signs

Supplementary-angle signs

Solution:

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