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Warm Up. Problem of the Day. Lesson Presentation. Lesson Quizzes. Warm Up Simplify. 1. 8 2 2. 12 2 3. 6.2 2 4. 7.5 2. 64. 144. 38.44. 56.25. Problem of the Day A 16 in. pizza sells for $11.99. A 10 in. pizza sells for $5.99. Which size gives you more pizza per penny? Explain.

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## Warm Up

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**Warm Up**Problem of the Day Lesson Presentation Lesson Quizzes**Warm Up**Simplify. 1. 82 2. 122 3. 6.22 4. 7.52 64 144 38.44 56.25**Problem of the Day**A 16 in. pizza sells for $11.99. A 10 in. pizza sells for $5.99. Which size gives you more pizza per penny? Explain. The larger pizza; you get more than twice as much (64 in2 instead of 25in2) for about twice the price.**Sunshine State Standards**Prep for MA.7.G.2.1 Justify and use formulas for surface area and volume of pyramids, prisms, cylinders, and cones. Review of MA.6.G.4.1**A circle can be cut into equal-sized sectors and arranged to**resemble a parallelogram. The height h of the parallelogram is equal to the radius r of the circle, and the base b of the parallelogram is equal to one-half the circumference C of the circle. So the area of the parallelogram can be written as 1 2 Cr. A = bh, or A = 1 2 Since C = 2r, A = (2r)r = r2.**Remember!**The order of operations calls for evaluating the exponents before multiplying. Additional Example 1A: Finding the Area of a Circle Find the area of the circle to the nearest tenth. Use 3.14 for . A = r2 Use the formula. 7 cm A 3.14 · 72 Substitute 7 for r. A 3.14 · 49 Evaluate the power. Multiply. A 153.86 The area of the circle is about 153.9 cm2.**Additional Example 1B: Finding the Area of a Circle**Find the area of the circle to the nearest tenth. Use 3.14 for . A = r2 Use the formula. A 3.14 · 92 Substitute 9 for r. 18 ft A 3.14 · 81 Evaluate the power. Multiply. A 254.34 The area of the circle is about 254.3 ft2.**Check It Out: Example 1A**Find the area of the circle to the nearest tenth. Use 3.14 for . A = r2 Use the formula. A 3.14 · 102 10 cm Substitute 10 for r. A 3.14 · 100 Evaluate the power. Multiply. A 314 The area of the circle is about 314 cm2.**Check It Out: Example 1B**Find the area of the circle to the nearest tenth. Use 3.14 for . A = r2 Use the formula. 12 ft A 3.14 · 62 Substitute 6 for r. A 3.14 · 36 Evaluate the power. Multiply. A 113.04 The area of the circle is about 113.0 ft2.**Additional Example 2: Application**Park employees are fitting a top over a circular drain in the park. If the radius of the drain is 14 inches, what is the area of the top that will cover the drain? Use 22 7 for . A = r2 Use the formula for the area of a circle. 22 7 ·142 Substitute. Use 14 for r. A 28 22 7 196 · A Evaluate the power. 1 A 22 · 28 Multiply. A 616 The area of the top that will cover the drain is about 616 in2.**Check It Out: Example 2**Albert was designing a cover for a spa. If the radius of the spa is 7 ft, what is the area of the cover that will be made? Use 22 7 for . A = r2 Use the formula for the area of a circle. 22 7 ·72 A Substitute. Use 7 for r. 7 22 7 49 · A Evaluate the power. 1 A 22 · 7 Multiply. A 154 The area of the top that will cover spa is about 154 ft2.**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. Substitute. Use 1.5 for r. A = 3.14 · 1.52 A 3.14 · 2.25 Evaluate the power. Multiply. A 7.07**1 2**Since of the circle is shaded, divide the area of the circle by 2. 7.07 ÷ 2 = 3.535. 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. 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. Substitute. Use 2.4 for r. A = 3.14 · 2.42 A 3.14 · 5.76 Evaluate the power. Multiply. A 18.09**3 4**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. 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. The area of the shaded region of the circle is about 13.56 cm2.**Lesson Quizzes**Standard Lesson Quiz Lesson Quiz for Student Response Systems**Lesson Quiz**Find the area of each circle, to the nearest tenth. Use 3.14 for . 1. 3. The bull’s-eye on a target has a diameter of 2 in.What is the area of the bull’s-eye to the nearest tenth? Use 3.14 for . 4. A round tablecloth has a radius of 36 in. What isthe area of the tablecloth? Use 3.14 for . Roundyour answer to the nearest tenth. 8 ft 2. 9 ft • 201.0 ft2 • 63.6 ft2 3.1 in2 4,069.4 in2**Lesson Quiz for Student Response Systems**1. Identify the area of the circle to the nearest tenth. Use 3.14 for . A. 907.5 ft2 B. 289 ft2 C. 226.9 ft2 D. 53.4 ft2 17 ft**Lesson Quiz for Student Response Systems**2. Identify the area of the circle to the nearest tenth. Use 3.14 for . A. 72.2 in2 B. 144.4 in2 C. 415.3 in2 D. 1661.1 in2 23 in.**Lesson Quiz for Student Response Systems**3. A round table has a diameter of 11 ft. What is the area of the table to the nearest tenth? Use 3.14 for . A. 95 ft2 B. 69.1 ft2 C. 54.2 ft2 D. 34 ft2

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