If O is the center of the circle above, what fraction of the circular region is shaded?
$\dfrac{1}{12}$
$\dfrac{1}{9}$
$\dfrac{1}{6}$
$\dfrac{1}{3}$
Explanation:
Vertical angles are congruent, so $150^{o}+150^{o}=300^{o}$ of the circle is not shaded.
Since there are $360^{o} $in a circle, this makes
$360^{o}−300^{o}=60^{o}$ of the circle shaded.
The fraction of the circular region that is shaded is thus
=$\dfrac{60}{360}$
=$\dfrac{1}{6}$