6.7 Circumference & Arc Length

6.7 Circumference & Arc Length 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!!! C = d C = (12) C = 12 C = 37.70 cm Ex 1: Find the circumference of a circle with a diameter of 12 cm. (Round to 2 decimal places.) OR

C = 2r 52 = 2r 8.28 in.  r Ex 2: Find the radius of a circle with a circumference of 52 in.

What if you only want to know the length of a piece of the circumference??? This is called Arc Length It is a piece of the circumference of circle. A B

Arc Length

Arc Length Corollary ( The length of AB is: Things to keep in mind when finding arc length • The measure of an arc is in degrees. • The length of an arc is in linear units. (such as ft, cm, etc.)

Ex 1: Find the length of JK. ( C 60o 16 in. J K

Your Turn: Find the length of AB. ( A 150o B 34 cm.

( Ex 2: Find the m LM.Notice that we are given the arc length and need to find the measure of the arc!! 16.76 in. L 8 in. M C

( Your Turn: Find the m AB. 18.84 m. B 9 in. A C

Ex 3: Find the circumference of circle C. R 10.2 cm S 45o C

Your Turn: Find the circumference of circle C. A 200o C 41.87 cm B

Your Turn: Find the radiusof circle C.READ the directions carefully!!! R 1.57 ft S 45o C

Practice Page 226 (1-19 all)

6.7 Circumference & Arc Length