Area of a circle:
Draw a circle either freehand or go to geogebra to create a circle, cut the circle into two semicircles. How could you make the semi circles form a parallelogram? A rectangle? What if you were to divide the circle in quarters or eighths?
Think about how the area of circle is related to the area of a parallelogram. See the video below for a complete explanation.
Watch the video below. How did your thinking compare to the video? Return to this page by using the back arrow.
You can also find the circumference of the circle by using the formula 2πr so you can also find the length of a part of a circle called an arc. Watch the following video to review finding the length of an arc.