Chapter 7, Problem 1SGA

To determine

To select: the letter of the term that matches best with the given equation or phrase.

Answer to Problem 1SGA

  $\text{b}$

Explanation of Solution

Given information:

  $\sin \frac{\alpha }{2}=\pm \sqrt{\frac{1-\cos \alpha }{2}}$

The terms given are as follows:

1. Sum identity
2. Half-angle identity
3. Normal form
4. Principal value
5. Pythagorean identity
6. Symmetry identity
7. Normal line
8. Double angle identity
9. Reciprocal identity
10. Quotient identity
11. Opposite-angle identity

Calculation:

The given equation i.e. $\sin \frac{\alpha }{2}=\pm \sqrt{\frac{1-\cos \alpha }{2}}$ is a half angle identity. Thus the term b. is correct.