1.7: Circles

A circle is the set of points in a plane at a given distance ( radius) from a given point (center). You name a circle by its center. The circle on the bicycle wheel with center O, is called circle O. Radius: segment from the center to a point on the edge of the circle.

Circle Terms

Point on Tangency: The point where the tangent touches the circle. Example: point B, and point C.

. R

S

. . Secant: Is a line that intersects the circle twice: 𝑹𝑺

Congruent Circles: Circles with the same radius.

Concentric Circles: Coplanar circles with the same center.

48° 132° 228° 312°

Are all Circles Similar?

A sequence of transformations that would always work to establish two circles to be similar would be a translation from one center to the other. This would form two concentric circles (circles with the same center). Once the circles share a common center then from that center point we could perform a dilation.

Are all Circles Similar?

Using a coordinate plane

Homework You will need a compass

On a separate sheet of paper:

Workbook 1.7: exercises 1-4, and

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