Chapter 5 - Section 5.3 - Double-Angle, Power-Reducing, and Half-Angle Formulas - Exercise Set - Page 682: 100

See graph. a. $y=sin(x)$ b. See explanations.

Graph the equation as shown in the figure. a. The graph appears to be the same as $y=sin(x)$ b. Using the identity $1+tan^2(x)=sec^2(x)$, we have $y=\frac{2tan(x/2)}{sec^2(x/2)}=\frac{2sin(x/2)cos^2(x/2)}{cos(x/2)}=2sin(x/2)cos(x/2)=sin(x)$