 # 6.7 Circumference & Area Notes. Circumference The distance around a circle. Do you remember the formula??? C = 2  r or C =  d * Always use the  button.

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6.7 Circumference & Area Notes

Circumference The distance around a circle. Do you remember the formula??? C = 2  r or C =  d * Always use the  button on your calculator, NOT 3.14!!!

C = 2  r C = 2  (6) C = 12  cm C = 37.70 cm * If you are asked for the exact value leave your answer in terms of . It will look like this!!! Ex 1: Find the circumference of a circle with a diameter of 12 cm. (Round to 2 decimal places.) C =  d C =  (12) C = 12  C = 37.70 cm OR

Ex 2: Find the radius of a circle with a circumference of 52 in. (Round to two decimal places.) C = 2  r 52 = 2  r 8.28 in.  r

Area The amount of space occupied. r A=  r 2

Find the area in terms of  and to the nearest hundredth.

Find the radius or diameter when you’re given the area: 1. Write the formula 2. Plug in what you know. 3. Solve for what you don’t know. The area of a circle is 52 square millimeters. Find the radius. Then, find the diameter.

If  S has a circumference of 10  inches, find the area of the circle to the nearest hundredth. C = 2  r 10  = 2  r 5 = r A =  r 2 A =  5 2 A =  25 A =  in 2

Class Work Textbook p. 226-227 #1-7, 20, 21; p. 228 #1-3

Homework Textbook p. 232 #1-9; p. 234 #1-9

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