# Circumferences and Areas of Circles COURSE 3 LESSON 8-8 The diameter of a small pizza is 24 cm. Find its area. Round to the nearest tenth. A = r 2 Use.

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Circumferences and Areas of Circles COURSE 3 LESSON 8-8 The diameter of a small pizza is 24 cm. Find its area. Round to the nearest tenth. A = r 2 Use the formula for area of a circle. = (12) 2 Substitute. The area of a small pizza is about 452.4 cm 2. Use a calculator.12 452.38934 The radius of the pizza is 24 ÷ 2, or 12 cm. Use the radius to find the area. 8-8

Circumferences and Areas of Circles Find the area of the unshaded region of the square tile with a circle inside of it, as shown below. Round to the nearest tenth. COURSE 3 LESSON 8-8 You can separate the figure into a circle and a square. Step 1 Find the area of the square. 8-8

Circumferences and Areas of Circles (continued) COURSE 3 LESSON 8-8 Area of square = s 2 Step 2 Find the area of the circle. Area of circle = r 2 A = (12) 2 Substitute 12 for s. = 144 Simplify. 113.1 Multiply. Round to the nearest tenth. A = (6) 2 Substitute 6 for r. 8-8

Circumferences and Areas of Circles (continued) COURSE 3 LESSON 8-8 Step 3 Subtract the area of the circle from the area of the square. The area of the shaded region is about 144 cm 2 – 113.1 cm 2 = 30.9 cm 2. 8-8

Circumferences and Areas of Circles Round to the nearest tenth. 1.Find the circumference and area of the circle. 2.Find the area. COURSE 3 LESSON 8-8 18.8 km; 28.3 km 2 273.0 in. 2 8-8

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