Circumference and area

What you'll learn

1. Compute the circumference of a circle using C = 2πr or C = πd, choosing the form that matches the given information
2. Compute the area of a circle using A = πr², converting from diameter to radius when necessary
3. Express answers in terms of π or as decimal approximations, as the problem requires
4. Solve for a missing radius or diameter given the circumference or area of a circle
5. Compute the area of shaded regions, semicircles, quarter circles, and annuli by combining circle formulas with other geometric reasoning

Prerequisites

• Radius, diameter, chord, secant, tangent