Lesson 66 of 1524
The Unit Circle: Sine and Cosine Functions
In addition to degrees, the measure of an angle can be described in radians
Practice this chapterIn addition to degrees, the measure of an angle can be described in radians To convert between degrees and radians, use the proportion θ 180 = θ R π
An angle is formed from the union of two rays, by keeping the initial side fixed and rotating the terminal side. An angle is in standard position if its vertex is at the origin and its initial side lies along the positive x -axis.
cosine function — the x -value of the point on a unit circle corresponding to a given angle. sine function — the y -value of the point on a unit circle corresponding to a given angle. unit circle — a circle with a center at ( 0 , 0 ) and radius 1. radian — the measure of a central angle of a circle that intercepts an arc equal in length to the radius of that circle.
Worked example
What does “cosine function” mean in The Unit Circle: Sine and Cosine Functions?
- 1Use the wording this chapter gives for cosine function.
- 2The book says: the x -value of the point on a unit circle corresponding to a given angle.
- 3Do not use the meaning of sine function. That term means the y -value of the point on a unit circle corresponding to a given angle.
Result: the x -value of the point on a unit circle corresponding to a given angle
Why. That is the meaning this chapter gives for cosine function.
Do not swap cosine function and sine function. cosine function means the x -value of the point on a unit circle corresponding to a given angle. sine function means the y -value of the point on a unit circle corresponding to a given angle.
Practice margin
This chapter
A fresh set from this chapter only. Choose 10 or 20. Multiple choice and fill-in, with no repeat inside the set.