Name: Date: Circles: Basic Properties of Circles · Circles: Basic Properties of Circles Pi (π) is...
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Name: ____________________ Date:_______________ www.softschools.com Circles: Basic Properties of Circles Pi (π) is a number whose value is described by the relationship between the circumference and diameter of a circle: π= C / d . From this relationship, we can find both circumference and diameter: Circumference: C = πd, or C = 2πr Diameter: d = C / π To find the area of a circle, use the formula A = πr 2 . Example: Practice. Find the circumference and area of the following figures. 1. r = 1.4 2. r = 4 C = C = A = A = 3. r = 5.2 4. r = 3.6 C = C = A = A = 5. r = 2.8 6. r = 6.28 C = C = A = A = 7. r = 4.3 8. r = 8 C = C = A = A = 9. r = 3.7 10. r = 1.8 C = C = A = A = r = 5 Area A = πr 2 A = π(5) 2 = π(25) = 3.14(25) = 78.5 Circumference C = 2πr = 2π(5) =10π =10(3.14) =31.4
Transcript of Name: Date: Circles: Basic Properties of Circles · Circles: Basic Properties of Circles Pi (π) is...
Name: ____________________ Date:_______________
www.softschools.com
Circles: Basic Properties of Circles
Pi (π) is a number whose value is described by the relationship between the
circumference and diameter of a circle: π=C/d. From this relationship, we can find
both circumference and diameter:
Circumference: C = πd, or C = 2πr
Diameter: d = C/π
To find the area of a circle, use the formula A = πr2.
Example:
Practice. Find the circumference and area of the following figures.
1. r = 1.4 2. r = 4
C = C =
A = A =
3. r = 5.2 4. r = 3.6
C = C =
A = A =
5. r = 2.8 6. r = 6.28
C = C =
A = A =
7. r = 4.3 8. r = 8
C = C =
A = A =
9. r = 3.7 10. r = 1.8
C = C =
A = A =
r = 5
Area
A = πr2
A = π(5)2
= π(25)
= 3.14(25)
= 78.5
Circumference
C = 2πr
= 2π(5)
=10π
=10(3.14)
=31.4
Name: ____________________ Date:_______________
www.softschools.com
Answer Key
Circle: Basic Properties of Circles
1. 8.70; 6.15
2. 25.12; 50.24
3. 32.66; 84.91
4. 22.61; 40.69
5. 17.58; 24.62
6. 39.44; 123.84
7. 27; 58.06
8. 50.24; 200.96
9. 23.24; 42.99
10. 11.30; 10.17
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