Start studying Consumer Math. The perimeter formula is one of the easier formulas to remember in math. Perimeter of a circle 2pr 2 p r r radius of the circle p constant r radius of the circle p constant Since we have a direct relationship between the radius r rand diameter d dof a circle.
If we know the diameter If we know the diameter of a circle the circumference can be found using the formula Perimeter P p D where.
Diameter of a circle D A07854. You find the area of a semicircle by plugging the given radius of the semicircle into the area of a semicircle formula. You sometimes see the word circumference to mean the curved line that goes around the circle. Area of circle 12 x Circumference x radius.