Finding Circumference Given Diameter/Radius II 4/29/15 Page 133 3. A bagel shop has a circular bagel sign in its parking lot with a radius of 4 feet. The shop owner is putting a string light on the outline of the sign. How much lighting is needed? The owner needs ____________ feet of lighting. Do Now: The circumference or distance around this circle is ___________ inches. Formula: Formula: 4. The circular lid of a barrel has a diameter of 62 centimeters. The circumference or distance around this lid is ___________ centimeters. Formula: Which formula do I use? = or = 2 1. The circumference or distance around this circle is ___________ mm. 5. The radius of a cup is 7 centimeters. Mr. Jow wants to find the circumference or distance around the cup so he multiplies (7) . Explain his error. Formula: Formula: Homework Use 3.14 for π unless otherwise told. 2. The shape of a snare drum head is a circle. The diameter of the drum head is 14 inches. The circumference or distance around this snare drum head is ___________ inches. Formula: 1. A. B. C. D. The diameter of the circular top of an oatmeal container is 10 centimeters. Which of the following expressions can be used to determine the circumference of the top of the oatmeal container in centimeters? 10 20 x 20 10 x 2. The diameter of a circular plate is approximately 6 inches. Find the circumference of the plate. Show work. x 6 = 18.84 in 3. The diameter of a wheel is 5 inches. If the wheel rolls 4 times, what is the distance it traveled? 11. A circular puzzle has a radius of about 50 inches. Which expression can be used to find the approximate circumference of this puzzle? x 5 x 4 = 62.8 inches 50 50 (2 ) 50 x (2 ) 50 x A. B. C. D. For questions, 4-8, TRUE OR FALSE 4. The length of the diameter of a circle is ½ the length of the radius of the circle. 12. The radius of a wheel is 4 inches. If the wheel rolls 5 times, what is the distance it traveled? FALSE 5. The length of the radius of a circle is twice the length of the diameter of the circle. 2X FALSE 6. X 4 X 5 = 125.6 inches The ratio of the circumference to the diameter of a circle is approximately 3 to 1. TRUE 7. Is the circumference about 3 times larger than the diameter? 13. The length of the radius is half the length of the diameter. TRUE 8. 1 Is the diameter about the length of the 3 circumference? TRUE 9. For questions, 13-14, TRUE OR FALSE Find the following properties: TRUE 14. The circumference is about 6 times longer than the radius. TRUE Diameter = 8 cm Radius = ___4_____ cm 15. Find the following properties: Circumference = 25.12 cm Diameter = ___6_____ cm Radius = 3 cm Circumference = _18.84_______ cm 10. Josue sliced an orange into circular pieces to put into a bowl of punch. The radius is 4 centimeters. Which expression can be used to find the approximate circumference of this piece of orange? A. 2(4) B. (4) C. 2( )(8) D. 2( )(4)

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