Using the circumference formula to find the size of Mr. Alvarado's head. Remember, you need to have a radius in order to find the circumference of a circle. Thank you to the students who helped and Mr. Alvarado for being a good sport. Example 1: 1:28 Example 2: 3:49 Example 3 (Practice Problems): 4:39 Follow me on Twitter: twitter.com/mathodman20 Follow me on Facebook: www.facebook.com/pages/Mathodman20/366316640049360