Answer
a) $60^{\circ} + 360^{\circ}k$ and $300^{\circ} + 360^{\circ}k$, for all integers $k$.
b) $60^{\circ}, 300^{\circ}$
Work Step by Step
b) Isolate $cos\theta$
$2cos\theta = 1$
$cos\theta = \frac{1}{2}$
Recall knowledge about the unit circle
$cos\theta$ is positive in quadrant I and IV - Angles $60˚$ and $300˚$
Therefore, $cos\theta = \frac{1}{2}$ for $\theta = 60˚, 300˚$
a) Take the two angles and add $360^{\circ}k$, for all integers $k$, to find all degree solutions.
$60^{\circ} + 360^{\circ}k$ and $300^{\circ} + 360^{\circ}k$, for all integers $k$.
