1. Circles and Circumference

2. Vocabulary A ________is a plane figure that consists of a set of points that are equidistant from a given point called the center. The ____________of a circle is the distance around it. circle circumference

3. Identifying the Parts of a Circle A __________is a line segment that connects the outside of the circle to its center. radius

4. A ______________is a line segment with both endpoints on the circle that passes through the center. diameter

5. A _________is a line segment whose endpoints are on the circle. Chords do not have to pass through the center of the circle. However, if a chord does pass through the center, it is also considered a _______________. chord

6. A diameter is a line segment with both endpoints on the circle that passes through the center.

7. A chord is a line segment whose endpoints are on the circle. Chords do not have to pass through the center of the circle. However, if a chord does pass through the center, it is also ______________________. Considered a diameter

8. Numerical Relationships A radius is exactly ________of a diameter. Therefore a diameter is _______a radius. 5.5 cm If the radius is 5.5 cm, then the diameter is ___________ cm. 11

9. Numerical Relationships A radius is exactly one-half of a diameter. Therefore a diameter is twice a radius. 5.5 cm If the radius is 5.5 cm, then the diameter is ___________ cm. 11

10. Circumference Remember, _____________is the distance around the circle. If you divide a circle’s circumference by its diameter, you ______________get the same irrational number – pi (symbol: ¶ ) This is true of every circle. We estimate pi to be 3.14 or the fraction 22/7.

11. Circumference Remember, circumference is the distance around the circle. If you divide a circle’s circumference by its diameter, you always get the same irrational number – pi (symbol: ¶ ) This is true of every circle. We estimate pi to be 3.14 or the fraction 22/7.