Find the first 4 positive solutions to each equation. (Use unit circle to make sense of each equation).

1. $\displaystyle sin2\theta=-\frac{1}{2}$

2. $\displaystyle cos2\theta=\sqrt{1-sin^2\theta}$

3.$\displaystyle cos\left [sin^-1 \frac{1}{2}+cos^-1 \frac{-\sqrt{3}}{2} \right ]$