#### Transcript 11.4

Five-Minute Check (over Lesson 11–3) Main Idea and Vocabulary Key Concept: Area of a Circle Example 1: Find the Area of a Circle Example 2: Real-World Example Example 3: Test Example • Find the areas of circles. • sector Find the Area of a Circle Find the area of the circle shown here. A = πr2 Area of a circle A = π ● 42 Replace r with 4. π × 4 x2 ENTER 50.26548246 Answer: about 50.3 cm2 Find the area of the circle shown here. A. approximately 32.97 ft2 B. approximately 65.9 ft2 C. approximately 121.3 ft2 0% D 0% C 0% B A D. approximately 346.4 ft2 0% 1. 2. 3. 4. A B C D KOI Find the area of the koi pond shown. The diameter of the koi pond is 3.6 m. Therefore, the radius is 1.8 m. A = πr2 Area of a circle A = π(1.8)2 Replace r with 1.8. A ≈ 10.2 Multiply. Answer: about 10.2 m2 COINS Find the area of a nickel whose diameter is 2.1 centimeters. A. approximately 2.5 cm2 B. approximately 3.3 cm2 C. approximately 3.5 cm2 D. approximately 4.5 cm2 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D Mr. McGowan made an apple pie with a diameter of 10 inches. He cut the pie into 6 equal slices. Find the approximate area of each slice. A 3 in2 B 13 in2 C 16 in2 D 52 in2 Read the Item You can use the diameter to find the total area of the pie and then divide that result by 6 to find the area of each slice. Solve the Item Find the area of the whole pie. A = πr2 Area of a circle A = π(5)2 Replace r with 5. A ≈ 78 Multiply. Find the area of one slice: 78 ÷ 6 = 13 Answer: B MERRY-GO-ROUND The floor of a merry-go-round at the amusement park has a diameter of 40 feet. The floor is divided evenly into eight sections, each having a different color. Find the approximate area of each section of the floor. A. 157 ft2 B. 225 ft2 1. 2. 3. 4. C. 264 ft2 0% D 0% C 0% B 0% A D. 312 ft2 A B C D End of the Lesson Five-Minute Check (over Lesson 11–3) Image Bank Math Tools Area of Trapezoids Drawing 3-D Figures Area of Polygons (over Lesson 11-3) Find the circumference of the circle. Use 3.14 for . Round to the nearest tenth if necessary. radius = 5 ft A. 15.7 ft B. 31.4 ft C. 78.5 ft D. 3.14 ft 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 11-3) Find the circumference of the circle. Use 3.14 for . Round to the nearest tenth if necessary. diameter = 11.2 in. A. 35.2 in. B. 17.6 in. C. 70.3 in. D. 7.0 in. 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 11-3) Find the diameter of the circle. Use 3.14 for . Round to the nearest tenth if necessary. C = 30 ft, diameter = ___ ft A. 9.5 B. 19.1 C. 9.6 D. 4.8 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 11-3) Find the diameter of the circle. Use 3.14 for . Round to the nearest tenth if necessary. C = 96 cm, diameter = ___ cm A. 24 B. 15.3 C. 3.0 D. 30.6 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 11-3) A coffee can has a circumference of 216 mm. Which equation could be used to find the diameter of the can in inches? A. 216 = d B. C = × 108 C. 108 = × d D. C = × 14.7 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D