Objective: Find the circumference and area of circles

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Objective: Find the circumference and area of circles.

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Objective: Find the circumference and area of circles Mr. Peter Richard Wears Cool Glasses Too! Objective: Find the circumference and area of circles

Circle – Label the parts Diameter Radius

Circumference: C=2 r Circumference is the length of the distance AROUND the circle Take 2 times the radius and pi

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Additional Example 3: Application Find the area of the shaded region of the circle. Use 3.14 for  . Round your answer to the nearest tenth. 1.5 cm The measurement of the radius of the circle is 1.5 cm. Now find the area of the entire circle. A = r2 Use the formula for the area of a circle. A = 3.14 · 1.52 Substitute. Use 1.5 for r. A  3.14 · 2.25 Evaluate the power. A  7.07 Multiply.

Additional Example 3 Continued Find the area of the shaded region of the circle. Use 3.14 for  . Round your answer to the nearest tenth. Since of the circle is shaded, divide the area of the circle by 2. 7.07 ÷ 2 = 3.535. 1 2 The area of the shaded region of the circle is about 3.5 cm2.

Check It Out: Example 3 Find the area of the shaded region of the circle. Use 3.14 for  . Round your answer to the nearest tenth. 2.4 cm The measurement of the radius of the circle is 2.4 cm. Now find the area of the entire circle. A = r2 Use the formula for the area of a circle. A = 3.14 · 2.42 Substitute. Use 2.4 for r. A  3.14 · 5.76 Evaluate the power. A  18.09 Multiply.

Check It Out: Example 3 Continued Find the area of the shaded region of the circle. Use 3.14 for  . Round your answer to the nearest tenth. Since of the circle is shaded, divide the area of the circle by 4 and subtract the answer from the entire area. 18.0864 ÷ 4 = 4.52. 18.0864 – 4.52 = 13.56. 3 4 The area of the shaded region of the circle is about 13.56 cm2.

Time To Circle Your Answers! Quiz: Worksheet Homework: Worksheet