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Circles: Piece of the Pi True or False

1. A circle divides a plane into ___ regions, including the circle itself. -> 1
2. In the following figure, points A, B, and C are on ⊙O. Which of the following angles are central angles of ⊙O?

-> ∠OBC only

3. The radius of ⊙P is 3 cm. What is the exact circumference of ⊙P? -> 6π cm
4. Suppose arc AB and arc CD are congruent. Which of the following is a true statement? -> Arc AB and arc CD have the same length, the same measure, and the same radius.
5. Arc ST has measure 60° and radius 6 cm. What is the exact length of arc ST? -> 2π cm
6. In the figure below, points A, B, and C are on ⊙O. If m∠AOB = 30° and ∠BOC is a right angle, what is the measure of arc ABC?

-> 30°

7. In the figure below, points A, B, C, and D are points on ⊙O and lines AC and BD intersect at O. m∠AOB = 24°. Distance OB is 5 km. What is the exact measure of arc BC?

-> 156°

8. Suppose arc LM and arc PQ have the same length. Which of the following must be true? -> Arc LM and arc PQ are congruent.
9. The circumference of ⊙O is exactly 56 m. Which of the following is closest to the radius of ⊙O? -> 9 m
10. A semicircle always _____. -> is an arc with measure 180°

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