Definition of a Circle Parts of a Circle Sector, Segment, Arc Length

1. CIRCLES
SECTOR, SEGMENT, ARC LENGTH

2. REVIEW
CIRCLE
- A set of all points in a plane that are equidistant from
a given point (the center)

3. REVIEW
RADIUS
- Segment whose endpoints are the center and any
point on the circle.

4. REVIEW
CHORD
- A line segment whose endpoints are on a circle.

5. REVIEW
DIAMETER
- Line segment that passes through the center of a
circle, and whose endpoints lie on the circle

6. REVIEW

7. CENTRAL ANGLE
- Angle formed by two radii
45º
90º
SECTOR
- Region bound by two
radii and an arc
containing them

8. SECTOR
measure of the central angle or arc
m
360
πr2
Area of a sector =
The fraction of the circle!
The area of the entire circle!

9. SECTOR
Find the area of the sector whose radius is 12m, and central
angle is 60°
A = m πr2
360
A = 60 (3.14)(12 m)2
360
A = 60 (3.14)(144 m2)
360
A = 27,129.6 m2
360
A = 75.36 m2
75.36 m2

10. SEGMENT
- Region bound by a chord and its corresponding arc.

11. SEGMENT
- Region bound by a chord and its corresponding arc.

12. SEGMENT
- Region bound by a chord and its corresponding arc.
The area of a segment
=
area of the sector
-
the area of the triangle