This document provides an overview of circular and periodic functions. It begins by stating the goals of finding trigonometric function values given a point on the unit circle or for special angles. It then defines key terms like unit circle and periodic functions. The document goes on to explain how the unit circle can be used to find exact trigonometric function values for special angles, and provides an example of using a point on the unit circle to find sine and cosine values. It concludes with an example of finding the six trigonometric function values for an angle measuring 5/4 radians.
2. Circular and Periodic Functions
2
Explore Trigonometric Functions of Special Angles
Todays Goals
Find value of trigonometric functions
given a point on a unit circle or the
measure of a special angle.
Find values of trigonometric
functions that model periodic events.
Todays Vocabulary
Unit circle
Circular functions
Periodic functions
Cycle
Period
3. Circular and Periodic Functions
Learn Circular Functions
A unit circle is a circle with a radius of 1 unit centered at the
origin on the coordinate plane. Notice that on unit circle, the
radian measure of a central angle =
1
or , so the radian
measure of an angle is the length of the arc on the unit circle
subtended by the angle.
You can use a point P on the unit circle to generalize sine and
cosine functions by applying the definition of trigonometric
functions in right triangles.
5. The unit circle is commonly
used to show the exact values
of and for special
angles. The cosine values are
the x-coordinates of the point
where the terminal sides of the
angles intersect the unit circle,
and the sine values are the y-
coordinates.
Circular and Periodic Functions
6. Example 1:
Find Sine and Cosine Given a Point on the Unit Circle
The terminal side of in standard position intersects the unit circle at
12
13
,
5
13
.
Find and :
12
13
,
5
13
= (, )
= __________
= __________
12
13
12
13
,
5
13
7. Example 1:
Find Trigonometric Values of Special Angles
Find exact values of the six trigonometric functions for an angle that measure
5
4
radians:
Using the unit circle, we know that special angle
5
4
intersect the unit circle in
Quadrant III at P
2
2
,
2
2
.
= _________ = _________