What did I needed to know in able to complete this mastery challenge

To complete this mastery challenge, I had to know how to convert the area of a circle to determine its radius and how to determine the area of an irregular shape. To determine the radius of the circle you need to divide the area of the circle by pi and determine the square root of the quotient to get the radius. To determine the area of an irregular shape, try breaking it up in smaller and less complex shapes, determining the area of those smaller shapes and then adding them together determine the area. To help you understand  these methods, try testing them with the pictures below.