Trigonometry Identities - Half Angle to Identity (Greek Letter)

Question

Complete the half-angle identity for this expression

$$	ext{sin}{(\frac{\alpha}{2})}$$

Accepted Answer

$$=\pm\sqrt{\frac{1-	ext{cos}(\alpha)}{2}}$$

Answer

$$=\pm\sqrt{\frac{1+	ext{cos}(\alpha)}{1-	ext{cos}(\alpha}}$$