6.1
Angles and Radian
Measure
Objective:
Change from radian to degree measure and vice versa.
Find the length of an arc given the measure of the
central angle.
Find the area of a sector.
Change 36° to radian measure in terms of
π
.
A
S
T
C
θ
O
A
H
135°
1
Given a central angle of 147°, find the length of
its intercepted arc in a circle of radius 10 cm.
Round to the nearest tenth.
First change the degree measure into radians.
radians
Second use the formula
s
=
r
θ
.
Where
s
is the arc
length,
r
is the radius, and
θ
is the measure of the
central angle in radians.
s
=
r
θ
A
=
π
r
2
Typical formula for area of a circle.
However, a sector is a portion of the circle. When
measured in radians, it is a portion of 2
π
. So we get
a portion of the area.
A
=
π
r
2
Assignment
6.1 Practice Worksheet
Unit Circle Worksheet