Warm up: Solve for x
124◦
1.)
2.)
53
145
70◦
x
18◦
x
3.)
260◦
80
x
4.)
70
110◦
x 20◦
EOC REVIEW
Question of the Day
Questions over hw?
Circumference,
Arc Length,
and, Area
Circumference
The distance
around a circle
Circumference
Twinkle, Twinkle Little Star
Circumference Equals 2 pi r
C = 2πr
or
C = πd
2 Types of Answers
Rounded
• Type the Pi
button on your
calculator
• Toggle your
answer
• Do NOT write Pi
in your answer
Exact
• Pi will be in
your answer
Find the EXACT circumference.
C = 2π (14 )
1.  r = 14 feet
C = 28π ft
2.  d = 15 miles
C = π (15 )
C = 15π miles
Ex 3 and 4: Find the circumference.
Round to the nearest tenths.
C = 2π (14.3 )
C = π ( 33 )
C = 89.8 mm
C = 103.7 yd
Arc Length
The distance along the curved line making
the arc (NOT a degree amount)
l
Arc Length
⎛ measure of arc° ⎞
Arc Length = ⎜
2π r
⎟
o
360
⎝
⎠
Ex 5. Find the Arc Length
Round to the nearest hundredths
⎛ measure of arc° ⎞
Arc Length = ⎜
2π r
⎟
o
360
⎝
⎠
⎛ 70 ⎞
Arc Length = ⎜
2π (8 )
⎟
⎝ 360 ⎠
• 8m
Arc Length = 9.77 m
70°
Ex 6. Find the exact Arc Length.
⎛ measure of arc° ⎞
Arc Length = ⎜
2π r
⎟
o
360
⎝
⎠
⎛ 120 ⎞
Arc Length = ⎜
2π (5 )
⎟
⎝ 360 ⎠
•
10
Arc Length =
π in
3
Ex 7. What happens to the arc length if
the radius were to be doubled? Halved?
⎛ measure of arc° ⎞
Arc Length = ⎜
2π r
⎟
o
360
⎝
⎠
20
Doubled
π
3
5
Halved π
3
•
Ex 8. Find the perimeter of the region.
30 + 9π units
Area of Circles
The amount of space occupied.
r
•
A=
2
πr
Find the EXACT area.
8. r = 29 feet
9. d = 44 miles
A = π ( 29)
2
A = 841π ft
⎛ 44 ⎞
A = π ⎜ ⎟
⎝ 2 ⎠
2
2
A = 484π mi
2
10 and 11
Find the area. Round to the nearest tenths.
A = π (7.6 )
⎛ 53 ⎞
A = π ⎜ ⎟
⎝ 2 ⎠
2
2
A = 181.5 yd
2
2
A = 2206.2 cm