The circle shown at right has a diameter of 20 cm. Homework Help ✎
What measurement do you need to find in order to calculate the area inside the circle?
Find the area inside the circle using the formula A = r2π. Write your answer as a product of r2 and π, and as an approximation using π = 3.14.
Recall the equation for area from the Math Notes box in this lesson.
A = r2 π
What measurement is missing in this equation?
Diameter = 2 (radius)
Solve for r.
Substitute the newly calculated radius into the area formula.
20 = 2 r
A = (10)2 π