Geometry
Notes Lesson 10.6
Name __________________________________
Circle Terminology
A circle is the set of all points equidistant from a given
point called the center.
______________________
A radius is a segment that has one endpoint at the center
and the other endpoint on the circle.
_____________ ____________ _____________
A diameter is a segment that contains the center of a circle and has endpoints on the circle. _________
A central angle is an angle whose vertex is the center of the circle. __________
Example.
The graph the to right shows how 3600 people spend their time in a
24-hour period.
1) What is the total number of degrees in a circle? _____________
2) 18% spend their time on Entertainment. How many degrees is 18%? ____________
3) Sleep? ________
4) Food? _________
Arc Terminology
An arc is a part of a circle. One type of arc, a semicircle is _______________________________________
A minor arc _____________________________________ A major arc _________________________________________
_________ is semicircle
_______ is minor arc
_______ is major arc
Example
In
C,
and
are diameters. Identify the following.
4. two major arcs
5. two minor arcs
6. two semicircles
7. a pair of adjacent arcs
8. an acute central angle
9. an obtuse central angle
Degrees of Arcs:
Semicircle = __________
Minor Arc _________________________
Major Arc ________________________
The measure of a minor arc is equal to its corresponding _____________________________________________.
The measure of a major arc is 360 - ______________________________________.
Example
Find the measure of each arc in
C.
15.
16.
17.
18.
19.
20.
Circumference of a Circle
Definition: The circumference is the ________________________________________________________________________.
Formula: C = ______________
Examples
Find the circumference of the circle. Leave your answers in terms of
1.
2.
.
3. The diameter of a bicycle shell is 22 in. To
the nearest whole number, how many revolutions
does the wheel make when the bicycle travels
100ft?
Arc Length
Arc Length =
measure of the arc
 2 r
360
Example
Find the length of each arc. Leave your answers in terms of
21.
.
22.
24. Find the length of a semicircle with radius 1.3m. Leave your answers in terms of
23.
.