Student materials: Copy of Circle Investigation, Scissors, Centimeter Ruler, and Yarn Circles  

Circumference of Circles 10.3 Notes Circumference of Circles     Determine the diameter if you don’t know it Copy the equation (don’t just solve in your head) Substitute the numbers for the variables Solve

I can… Find the diameter of a circle Find the radius of a circle Calculate the circumference of a circle Self Assessment 5- I can do it without help & teach others. 4- I can do this with no help, but I don’t know if I can explain it. 3- I can do this with a little help. 2- I can do this with a lot of help! 1- I don’t have a clue.

Center

Radius

Radii

Diameter

Circumference

Chord

2r = d Radius + Radius Diameter 2)d = r 2 X Radius = Diameter Diameter ÷ 2 = Radius

A. 1 in B. 3 in 3 in D = ? C. 6 in D. 12 in

A. 3 in B. 6 in 6 in D = ? C. 9 in D. 12 in

A. 3 in B. 6 in 6 in R = ? C. 9 in D. 12 in

A. 1.5 in B. 3 in 3 in R = ? C. 6 in D. 12 in

Using the provided circle templates, you and your teammate(s) will: Circle Investigation Using the provided circle templates, you and your teammate(s) will: Cut out circle templates Measure the radius and diameter of each circle to the nearest tenth of a centimeter Measure the circumference with yarn and then measure the yarn to the nearest tenth of a centimeter Divide the circumference by the diameter Fill in the table for each circle Discuss and answer questions on the bottom of the worksheet

Investigation Discussion How is the radius related to the diameter? How are the radius and the circumference related? How are the diameter and the circumference related?

Circumference How do you find the circumference of a circle? is the symbol for the Greek letter Pi.

Pi is an irrational number.

3.1415926538979323846... 3.14

Circumference C = πd D = π)c Pi = π 3.14 = Pi Diameter x 3.14 = Circumference 3.14 = Pi D = π)c Pi = π

C = πd 8 ft 25.12 2.512 24.32 24.82 3.14 = Pi

C = πd 15 cm 32.46 46.21 47.1 74.1 3.14 = Pi

C = πd 25 cm 75.83 57.8 5.78 78.5 3.14 = Pi

C = πd 10 m 62.8 6.28 31.4 3.14 3.14 = Pi

C = πd 15 m 4.71 47.1 92.4 94.2 3.14 = Pi

40 yds R = ? 20 40 60 80

16 m R = ? 4 8 16 32

20 cm D = ? 10 20 30 40

16 ft D = ? 8 16 32 48

I can… Find the diameter of a circle Find the radius of a circle Calculate the circumference of a circle Self Assessment 5- I can do it without help & teach others. 4- I can do this with no help, but I don’t know if I can explain it. 3- I can do this with a little help. 2- I can do this with a lot of help! 1- I don’t have a clue.

Circumference of Circles 10.3 Notes Circumference of Circles     Determine the diameter if you don’t know it Copy the equation (don’t just solve in your head) Substitute the numbers for the variables Solve