Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A =...
Transcript of Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A =...
![Page 1: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/1.jpg)
Area & Circumference of Circles
![Page 2: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/2.jpg)
Circumference of a Circle: outside/ perimeter of a circle.
Formula: C = 2pr
r = radius
18cmC = 2pr
C = 2(p)(18)
Example 1
C = 36p cm
113.04 cm
![Page 3: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/3.jpg)
Example 2 Example 3
26ft
C = 16p m
Find the radius.d = 26 ft
r = 13 ft
C = 2(13)(p)
C = 26p ft
C = 2(p)r
16p = 2(p)r
r = 8m
p cancels out.
![Page 4: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/4.jpg)
Area of a Circle – remember to label with units2.
Formula: A = pr2
r = radius
18cmA = pr2
A = (p)(324)
A = 324p cm2
1017.36 cm2
Example 1:
![Page 5: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/5.jpg)
Example 2 Example 3
26ft
A = 16p m2
Find the radius. d = 26ft
r = 13ft
A = (132)(p)
A = 169p ft2
A = pr2
16p = pr2
16 = r2
r = 4m
![Page 6: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/6.jpg)
Area of Sectors
Arc Length
![Page 7: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/7.jpg)
Arc Length – a portion (or fraction) of the whole circumference.
Ex1.Find the length of a semicircle.
10cm
First, find the whole circumference:
C = 2pr
C = 2(p)(10)
C = 20p cm
Multiply your answer by ½ :
10p cm
![Page 8: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/8.jpg)
A
Bx°
Formula:
Arc Length = ( )r2360
xp
Circumference
Fraction of the circle
![Page 9: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/9.jpg)
Example 2 – Find the length of AB.
A
B13015in
( )r2360
xp
( )152360
130p
inp6
65
![Page 10: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/10.jpg)
Example 3A
B6in
Find the length of AB.
3p in 6p m
Example 4
18m
A
B60
Find the length of AB.
( )rx
p2360
( )rx
p2360
( )62360
90
p ( )182
360
60
p
![Page 11: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/11.jpg)
Area of a Sector – a region of a circle created by two radii; a portion (or fraction) of the entire area.
Formula:
Area of Sector = ( )2r360
xp
A
Bx
Area
Fraction of the circle
Q
![Page 12: Area & Circumference of Circles...Area of a Circle –remember to label with units2. Formula: A = pr2 r = radius 18cm A = pr2 A = (p)(324) A = 324p cm2 1017.36 cm2 Example 1:](https://reader034.fdocuments.us/reader034/viewer/2022052020/6033fecf0921a905c10261c3/html5/thumbnails/12.jpg)
Example 1A
B6in
Find the area of sector AQB
9p in2 24p m2
Q
Example 2
12m
A
B60
Find the area of sector AQB.
Q
( )2r360
xp
( )26360
90p
( )2r360
xp
( )212360
60p