Area and circumference of circles
Key Notes :
The circumference of a circle is C=2𝜋r or C=𝜋d.
Learn with an example
The radius of a circle is 10 kilometers. What is the circumference?
Give the exact answer in simplest form. _______kilometers.
Find the circumference.
C=2𝜋r
=2𝜋(10) Plug in r=10
=20𝜋 Multiply
The circumference is 20𝜋 kilometers.
The radius of a circle is 10 centimeters. What is the circumference?
Give the exact answer in simplest form. _________centimeters.
Find the circumference.
C=2𝜋r
=2𝜋(10) Plug in r=10
=20𝜋 Multiply
The circumference is 20𝜋 centimetres.
The radius of a circle is 3 meters. What is the circumference?
Give the exact answer in simplest form. _________meters
Find the circumference.
C=2𝜋r
=2𝜋(3) Plug in r=3
=6𝜋 Multiply
The circumference is 6𝜋 metres.
let’s practice!
