Circumference of a circle (59) Note: BOOK 1
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59 Circumfernce of circles.notebook 1 March 17, 2015 Mar 128:24 AM The circumference is abut 3 times the measure of the diameter. The diameter is twice the radius. Circumference of a circle (59) Note: BOOK 1
Transcript of Circumference of a circle (59) Note: BOOK 1
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The circumference is abut 3 times the measure of the diameter.
The diameter is twice the radius.
Circumference of a circle (59)
Note: BOOK 1
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The more precise approximation for is using the pi button on your calculator as it brings the value of pi out 9 place values after the decimal point.
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Formula:
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What if the circumference is given to us? How do we find the radius or diameter? Use 3.14 for pi.
a) The circumference is 37.68 ft. Find the radius and the diameter.
b) The circumference is 75.36 cm. Find the radius and the diameter.
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Find the circumference of the following: Leave your answer in terms of pi.
a) when the diameter is 14:
b) when the radius is 11:
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50 ft12 in.12 in.
Let's discuss...
How would you find the circumference of the following:
a) b)
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Circumference is the distance around a circle.
It is calculated by ...
1) Use the string to measure the distance around the circle. This representsthe circumference of the circle. Cut the length of the circumference fromthe string.
2) Use the remaining string to measure the distance across the circle. Thisrepresents the diameter of the circle. Reminder the diameter must pass through the center of the circle. Cut the length of the diameter from the string.
Demonstration
4) Write a ratio (in fraction form) comparing the circumference of the circleto the diameter of the circle.
3) Using a ruler, measure the following:a) the length of the string representing the circumference.b) the length of the string representing the diameter.
5) Convert the ratio into a decimal. Round to the nearest hundredth.
6) Let's share and discuss our findings...
STEPS:
7) Using what we have just learned, write the formula for the circumferenceof a circle.
The exact value of the ratio is represented by the Greek letter
You will notice that
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