Question

If $\theta$is acute, the Half-angle Formula for the cosine function is$\cos \frac{\theta }{2}=\_\_\_\_\_\_\_$.

Short answer

If $\theta$is acute, the Half-angle Formula for the cosine function is$\cos \frac{\theta }{2}=\underline{\pm \sqrt{\frac{1+\cos \theta }{2}}}$.

Step-by-step solution

Step 1. Given information

The incomplete statement is " If $\theta$is acute, the Half-angle Formula for the cosine function is$\cos \frac{\theta }{2}=\_\_\_\_\_\_\_\_$."

Step 2. Fill in the blank.

The half-angle formula for the cosine function is given with the following expression:

$\cos \frac{\theta }{2}=\pm \underline{\sqrt{\frac{1+\cos \theta }{2}}}$.