Answer 4.4:7
From Förberedande kurs i matematik 1
| a) | \displaystyle \left\{ \matrix{
x=\displaystyle \frac{\pi}{6}+2n\pi\cr x=\displaystyle \frac{5\pi}{6}+2n\pi\cr x=\displaystyle \frac{3\pi}{2}+2n\pi }\right. | b) | \displaystyle x=\pm \displaystyle \frac{\pi}{3} + 2n\pi |
| c) | \displaystyle \left\{ \matrix{
x=\displaystyle \frac{\pi}{2}+2n\pi\cr x=\displaystyle \frac{\pi}{14}+\displaystyle \frac{2n\pi}{7} }\right. |
