1. Lesson _______ Section 4
Lesson _______ Section Intro to Trigonometry: Radian & Degree Measure
Triangle
Measurements
Vocabulary
Origin & Quadrants
Vertex
Right, Acute, & Obtuse
Complementary & Supplementary
Central & Inscribed Angles
Arc

2. An ANGLE is created by rotating a ray about its endpoint (vertex).
Terminal Side
Initial Side
If we fit an angle to a coordinate system, the vertex is at the _______ and the initial side is the _________
This is called “Standard Position”

3. Positive Angle (Counterclockwise)
Negative Angle (Clockwise)
These 2 angles are “COTERMINAL”
(They end together)
Ex. Find 2 angles that are coterminal with 100°

4. Angles can be measured in DEGREES or in RADIANS (similar to feet & meters)

5. s  r If s = r then  = 1 radian
DEF: One RADIAN is the measure of a central angle  such that the arc length s is equal to the length of the radius r. s
If s = r then
 = 1 radian  r

6. The radian measure of a central angle 10 5
1 rad.
2 rad. 5 5
The radian measure of a central angle  =
arc length s r =
radius

7. = s r  360° 180° 90° 60° 45° 30° ? ½ a revolution? ¼ a revolution? 2
Radians
Degrees
360°
1 full revolution?
½ a revolution?
180°
¼ a revolution?
90°
60° s r = 
45°
30° ? 2

8. Sketch the following angles:
Ex.

9. Ex. What is the supplement of ?
Ex. What is the complement of ?
Ex. Find 2 coterminal angles for
for

10. THETA must be measured in RADIANS!
ARC LENGTH FORMULA s r =  s r = 
THETA must be measured in RADIANS!