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2. Lesson Menu Five-Minute Check (over Lesson 10–1) Main Idea and Vocabulary Key Concepts: Radius and Diameter Example 1:Find the Radius Example 2:Find the Diameter Key Concept: Circumference Example 3:Estimate the Circumference Example 4:Estimate the Circumference Example 5:Use a Calculator to Find Circumference Example 6:Choose the Correct Method

3. Main Idea/Vocabulary circle center chord diameter circumference radius Estimate and find the circumference of circles.

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5. Example 1 Find the Radius The diameter of a circle is 48 centimeters. Find the radius. Answer: The radius is 24 centimeters. d

6. 1.A 2.B 3.C 4.D Example 1 A.2 m B.8 m C.16 m D.32 m The diameter of a circle is 16 meters. Find the radius.

7. Example 2 Find the Diameter The radius of a circle is 9 inches. Find the diameter. Answer: The diameter is 18 inches. d = 2rDiameter of circle

8. 1.A 2.B 3.C 4.D Example 2 A.11 cm B.22 cm C.44 cm D.88 cm The radius of a circle is 22 centimeters. Find the diameter.

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10. Example 3 Estimate the Circumference Estimate the circumference of the circle. Answer: The circumference is about 18 meters. Replace π with 3 and d with 6. C = π d

11. 1.A 2.B 3.C 4.D Example 3 A.6 yd B.8 yd C.12 yd D.16 yd Estimate the circumference of the circle.

12. Example 4 Estimate the circumference of the circle. Answer: The circumference is about 90 millimeters. Estimate the Circumference Replace π with 3 and r with 15. C = 2 π r

13. 1.A 2.B 3.C 4.D Example 4 A.8 in. B.12 in. C.24 in. D.72 in. Estimate the circumference of the circle.

14. Example 5 C = 2 ● π ● 3Replace r with 3. Use a calculator to find the circumference of the circle. Round to the nearest tenth. Answer: Rounded to the nearest tenth, the circumference is 18.8 yards. Use a Calculator to Find Circumference C = 2 π r 2318.84955592 ENTER× π ×

15. 1.A 2.B 3.C 4.D Example 5 A.7.9 cm B.15.7 cm C.37.7 cm D.75.4 cm Use a calculator to find the circumference of the circle. Round to the nearest tenth.

16. Example 6 A Divide the diameter by π. B Multiply the radius by π. C Multiply the diameter by 2, and then multiply by π. D Multiply the diameter by π. Anna knows the diameter of a basketball hoop but would like to find the circumference. Which method can she use to find the circumference of the basketball hoop? Read the Item You need to find the circumference of the basketball hoop. You know the diameter of the basketball hoop. Choose the Correct Method

17. Example 6 Answer: D Solve the Item Use the formula for the circumference of a circle, C = π d. The formula states that the circumference of a circle is equal to π times the diameter. Choose the Correct Method

18. 1.A 2.B 3.C 4.D Example 6 A standard baseball has a circumference of 9 inches. Which method can be used to find the radius of the baseball? A.Divide the circumference by π and then multiply by 2. B.Divide the circumference by π and then divide by 2. C.Multiply the circumference by π and then multiply by 2. D.Multiply the circumference by π and then divide by 2.

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20. Resources Five-Minute Check (over Lesson 10–1) Image Bank Math Tools Using a Net to Build a Cube Area of Triangles

21. 1.A 2.B 3.C 4.D Five Minute Check 1 A.10 in. B.11 in. C.12 in. D.22 in. Find the perimeter of the figure. (over Lesson 10-1)

22. 1.A 2.B 3.C 4.D Five Minute Check 2 A.48 ft B.83 ft C.96 ft D.166 ft Find the perimeter of the figure. (over Lesson 10-1)

23. 1.A 2.B 3.C 4.D Five Minute Check 3 A.145 cm B.48 cm C.24 cm D.12 cm Find the perimeter of the figure. (over Lesson 10-1) 15 cm 9 cm

24. 1.A 2.B 3.C 4.D Five Minute Check 4 A.34 m B.51 m C.68 m D.85 m Find the perimeter of the figure. (over Lesson 10-1)

25. 1.A 2.B 3.C 4.D Five Minute Check 5 A.75 ft B.150 ft C.232 ft D.360 ft What is the perimeter of a rectangular parking lot that measures 52 feet by 128 feet? (over Lesson 10-1)

26. 1.A 2.B 3.C 4.D Five Minute Check 6 A.12 in. B.11 in. C.10 in. D.9 in. What is the length of a piece of paper that is 10 inches wide and has a perimeter of 44 inches? (over Lesson 10-1)

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