A circle is the set of all points equal in distance from a center point. If you pinned a piece of yarn down, then tied a pencil to the other end of the yarn and pulled the pencil around, you'd roughly draw a circle.
Here are some more definitions that you need to know.
- Chord: a line segment connecting two points on a circle.
- Radius: the distance from the center of a circle to a point on the circle.
- Diameter: the distance across a circle, through the center of a circle. The diameter can be made by putting two radii together, end to end. The diameter is equal to two times the radius, or d = 2r.
- Secant: a line intersecting a circle at two points.
- Tangent: a line intersecting a circle at exactly one point.
All circles are similar, meaning that they have the same shape but may be different sizes.
Example 1
You're standing on a circle and you're 3 feet from the center point of the circle. If you move to another point on the circle, how far will you be from the center point? |
Example 2
Label each line on the circle below.
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Example 3
Is this statement true or false?
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