Question

find a cofunction with the same value as the given expression. sin 51° select the correct choice below and fill in the answer box to complete your choice. (simplify your answer. type any angle measures in degrees. do not include the degree symbol in your answer.) a. sin 51° = csc □° b. sin 51° = cot □° c. sin 51° = sec □° d. sin 51° = cos □° e. sin 51° = tan □°

Explanation:

Step1: Recall cofunction identity

The cofunction identity for sine and cosine is $\sin\theta = \cos(90^{\circ}-\theta)$.

Step2: Apply the identity to $\sin 51^{\circ}$

Substitute $\theta = 51^{\circ}$ into the identity: $\sin 51^{\circ}=\cos(90 - 51)^{\circ}=\cos 39^{\circ}$. So the correct option is D, and the angle is 39.

Answer:

D. $\sin 51^{\circ}=\cos 39^{\circ}$