Circles

Semi-circle perimeter

Finding the perimeter of semi-circles using the formula $\large~P\,=\,\frac{\pi~d}{2}\,+\,d$.

Practice using 3 1/7 to find area and circumference

Practice using $3\frac{1}{7}$ to find area and circumference.

Practice using 3.14 to find area and circumference

Practice using 3.14 to find area and circumference

Area of semi-circles

Teaser and introduction goes here. Sample problem here.

Circles

This is the "title" page for the Circles book.

Finding π Experimentally

Students measure the circumference and diameter of several different circles in order to find a good estimation for π.

Area of circles

Finding the area of circles using the formula π • r • r

Why is the area of a circle π•r•r?

Watch this video to learn why the formula for the area of a circle is π • r • r.

Semi-circle "Circumference"

Finding the length of a wire that is bent into a semi-circle is just a little tricky. This lesson will help you learn how!

Circumference

Learn how to find the circumference of a circle if you know the measure of the circle's diameter. $$C\,=\,\pi~\cdot~d$$