The circle shown has center $O$, and diameters $AB$ and $CD$. The length of arc $AC$ is three times the length of arc $CB$. What is the central angle $∠BOD$ in radian?
Answer:
B
Explanation
The correct answer is Choice B.
Use the given value of the circumference and the ratio of arc lengths to determine the arc length $BD$.
Choice A is incorrect because this is the angle of $AOD$.
Choice C is incorrect because this is would make the ratio of the two arcs, $CB$and $BD$, equal 1:1.
Choice D is incorrect because this is the angle of a straight line.
✨ Expert's Tip ✨
A straight line forms $180^{\circ}$or $\pi$.