Warm-Up
• Find the area of the shaded region.
Diameter = 8 inches
Geometry 11-2 and 11-3
Arcs
Definition
• A central angle is an angle whose vertex
is the center of a circle.
• An arc is the distance between two points
on a circle.
central angle: x
arc: AC
Types of Arcs
• Minor arc: needs only two letters to name it
– The measure of the arc is the same as the
measure of the angle
• Major arc: needs three letters to name it
-more than half of the circle
-measure = 360 - x
Minor arc
Major arc
Example
Find mKLF.
Definition
A sector area of a circle is the area of a shaded
portion of the cirlce.
Sector Area = (area of circle) x (fraction of circle shaded)
Example
• Find the area of the shaded sector JGH.
Definition
An arc length of a circle is the distance around a
circle between two points.
Arc length= (circumference of circle) x (fraction of circle)
Example
• Find the arc length of FG.
Example
• Richard is going to build a fence around a
portion of his circular garden. How many feet
of fence will Richard need to complete the job?
18 ft