May 15, 2015

Students use inscribed and circumscribed polygons for a circle (or disk) of radius r and circumference C to show that the area of a circle is (1/2)Cr or as it is usually written, ?r^2.

Teacher and Student versions of full lesson from engageNY

- Mathematics > General
- Mathematics > Geometry

- Grade 9
- Grade 10

Reason abstractly and quantitatively.

Construct viable arguments and critique the reasoning of others.

Model with mathematics.

Use appropriate tools strategically.

Attend to precision.

Give an informal argument for the formulas for the circumference of a circle, area of a circle, volume of a cylinder, pyramid, and cone.