Circles and Similarity

Sean has two circles, one with a radius of 1 inch and another with a radius of 3 inches.

What is the ratio between the radii of the circles?

What is the scale factor between the two circles?

What is the ratio between the circumferences of the circles?

What is the ratio between the areas of the circles?

What do area ratios and circumference ratios have to do with scale factor?

Lessons, videos, exercises, and text from CK-12.

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- Mathematics > General
- Mathematics > Geometry

- Grade 9
- Grade 10

Reason abstractly and quantitatively.

Construct viable arguments and critique the reasoning of others.

Attend to precision.

Look for and make use of structure.

Prove that all circles are similar.