Solution 4.2:5c
From Förberedande kurs i matematik 1
If we express the angle 330° in radians, we obtain
| \displaystyle 330^{\circ} = 330^{\circ}\cdot \frac{\pi}{180^{\circ}}\ \text{radians} = \frac{11\pi}{6}\ \text{radians} |
and from exercise 3.3:1g, we know that
| \displaystyle \cos 330^{\circ} = \cos \frac{11\pi}{6} = \frac{\sqrt{3}}{2}\,\textrm{.} |
