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DETERMINE THE AREA AND CIRCUMFERENCE OF A CIRCLE • The circumference of a circle is the distance around the outside. • The diameter of a circle is the distance across the inside of a circle through the center. • The radius of a circle is half the diameter. • The circumference is calculated by multiplying the diameter of the circle times the value of pi (п) which is approximately 3.14 → C = пD • The area of a circle is the space contained within the circumference. It is measured in square units. • The area of a circle is calculated by multiply pi (п) t imes the radius squared → пr2 How to determine the area and circumference of a circle: • Use the formula C = п x D to calculate the circumference of a circle. • Input the length of the diameter and perform the operation. C = п x D D = 15 cm C = 3.14 X 15 C = 47.10 cm. C = п x D D = 8 cm C = 3.14 X 8 C = 25.12 cm. • Use the formula A = п x r2 to calculate the area of a circle. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

• Input the length of the radius and perform the operation. A = п x r2 D = 12 cm → r = 6 cm A = 3.14 X 62 A = 3.14 X 36 A = 113.04 sq. cm A = п x r2 D = 20 cm → r = 10 cm A = 3.14 X 102 A = 3.14 X 100 A = 314 sq. cm • To determine the circumference or the area of a circle choose either the formula C = п x D or the formula A = п x r2. Input the values and complete the operations. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.

Try This! 1. What is the area of a circle with a diameter of 24 inches? ________________________________________________________ 2. What is the area of a circle with a radius of 15 cm? ________________________________________________________ 3. What is the circumference of a circle with a diameter of 17 feet? ________________________________________________________ 4. What is the circumference of a circle with a diameter of 30 feet? ________________________________________________________ 5. What are the circumference and the area of a circle with a diameter of 8 cm? ________________________________________________________ © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.