Question
Use the cofunction and reciprocal identities to complete each of the following.$$\cos 20^{\circ}=\text{_____}70^{\circ}=\frac{1}{\text{____}20^{\circ}}$$
Step 1
Step 1: We know that the cofunction identity states that $\cos(\theta) = \sin(90 - \theta)$. Show more…
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