The Unit Circle and Cosine and Sine Functions

The Unit Circle and the Cosine and Sine Functions

In this module we will introduce and study the two basic trigonometric functions – Cosine and Sine. As we will see any point in the x-y plane is some (radial) distance r away from the origin on a line through the origin. Since a line through the origin is inclined at some angle θ the coordinates  of x and y  of any point in the plane can be written in terms r  and cosine and sine of the angle θ.

Review: Pythagorean Theorem for right angle triangles, positive and negative angles, radian and degree measures.

Learning Objectives:

  • Equation of a circle of radius r and center (0,0e).
  • Equation of the Unit Circle
  • Reference angle
  • Definition of Cosine and Sine
  • Domain and Range of the Cosine and Sine Functions