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Practice finding the circumference of circles using the formula C = 2πr or C = πd. Solve problems and round to the nearest tenth if necessary.
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DO NOW Complete number 6 (Area and Perimeter) on sheet 6-8
Chapter 6lesson 9 Circles and circumference Objective: Find the circumference of circles
Vocabulary Circle: the set of all points in a plane that are the same distance from a given point called the center. center
Vocabulary Radius: r The distance from the center to any point on a circle. Circumference: C The distance around the circle Diameter: d The distance across a circle through the center
Pi 3.14159… Where has Pi come from?
Pi: The ratio of the circumference of a circle to its diameter. The circumference is 3.14… times the diameter. d
The circumference of a circle C = d or C = 2 r
To solve each problem make sure you solve using the 4 steps! F: Formula P: Plug it in S: Solve A: Answer
Lets try some C = d or C = 2 r 8 ft C = 2 x 3.14 x 8 C = 16 x 3.14 C = 50.24 C= 50.2 ft Find the circumference of each circle. Round to the nearest tenth if necessary.
Lets try some Find the circumference of each circle. Round to the nearest tenth if necessary. C = d or C = 2 r 14 m C = 3.14 x 14 C = 43.96 C = 44 m
Lets try some more!! Find the circumference of each circle. Leave your answer in terms of pi. C = d or C = 2 r C = 2 x x 11.7 C = 23.4 x C = 23.4 cm Radius = 11.7 cm
Lets try some Find the circumference of each circle. Leave your answer in terms of pi. C = d or C = 2 r C = x 3.5 C = 3.5 yd diameter = 3 ½ yd
Turn to page 276 in your textbooks Do numbers 11 and 12 ( solve out answer) And Numbers 13 and 15 (answer in terms of pi)