circumference review. review what is the relationship between a radius and a diameter? what does a...
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Circumference Review
Review
• What is the relationship between a radius and a diameter?
• What does a circumference measure?
• What formulas do we use to calculate circumference?
• What do we use to represent pi?
Pi Equals?
• π = circumference/diameter
≈
• π ≈ 22/7 or 3 and 1/7
• We will use 3.14
3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273………. (on and on and on)
Find the Circumference of the circle.
rC 2
214.32C
yd. 56.12CBACK
Find the circumference using the diameter.
π dC
1014.3C
in. 4.31C
BACK
Calculate the following
• Using 3.14 for pi.– r = 6– r = 13
• Using 22/7 for pi. – r = 8– d = 24
Circumference 2 Assignment
• Use 3.14 for pi1) r = 4
2) r = 7
3) r = 9
4) d = 15
5) d = 22
6) d = 30
• Use 22/7 for pi1) r = 4
2) r = 7
3) r = 9
4) d = 15
5) d = 22
6) d = 30
Area of a Circle
Area
• The number of square units the figure covers
Area of a Circle
2 rA 2514.3A
2514.3A2in. 5.78A
Find the Area of the circle.
2 rA 2214.3A
414.3A2yd 56.12A
Find the Area of the circle.
2 rA
2814.3A
6414.3A2ft. 96.200A
Practice Problems
• Using 3.14 for pi– r = 6– d = 14
• Using 22/7 for pi– r = 8– d = 24
Area of a Circle1 Assignment
• Use 3.14 for pi1) r = 4
2) r = 9
3) d = 16
4) d = 22
• Use 22/7 for pi1) r = 4
2) r = 9
3) d = 16
4) d = 22
Area of a Circle
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