1. Splash Screen

2. Over Lesson 11–6 5-Minute Check 1

3. Then/Now You have already found the perimeter of rectangles. (Lesson 5–1) Find the circumference of circles. Solve problems involving circumference.

4. Concept 1.Use the ruler to measure the diameter of the cylinder (in inches) and record it in your notebook. 2.Use the tape measure to estimate the circumference (in inches). Make sure you use the yellow side! 3.What is the relationship between the circumference and the diameter? Circumference Activity

5. Concept Circumference - the distance around the circle  (pi) – the ratio of the circumference to the diameter

6. Concept

7. Example 1 Find the Circumference of a Circle Find the circumference of the circle. Round to the nearest tenth. C=  dCircumference of a circle =  ● 12Replace d with 12. =12  Simplify. This is the exact circumference. Answer: The circumference is about 37.7 inches. To estimate the circumference, use a calculator. ENTER×2nd 12[  ]37.69911184

8. Example 1 A.12 ft B.12.6 ft C.25.1 ft D.50.3 ft Find the circumference of the circle to the nearest tenth.

9. Example 2 Find the Circumference of a Circle Find the circumference of the circle. Round to the nearest tenth. Answer: The circumference is about 44.6 meters. C=  dCircumference of a circle =  ● 14.2Replace d with 14.2.  44.6Simplify. Use a calculator. r = 7.1 m d = 7.1 x 2 = 14.2 m

10. Example 2 A.5.0 cm B.8.0 cm C.10.1 cm D.32.2 cm Find the circumference of the circle to the nearest tenth.