Inscribed angles:

The measure of the inscribed angle is half the angle of the central angle (remember that central angles and intercepted arcs have the same measure).

Evaluate Cosine

Signs of Sin, Cos and Tan in Each Quadrant  ​

​What is a Quadrant?

Each of the 4 quarters of a circle

• Quadrants of a circle are numbered

  going counter clockwise​

• The quadrant determines whether

  the x and y values are positive

  or negative​

Using the Unit Circle

• To use the Unit Circle to evaluate cosine, sine, or tangent we use the coordinates of the point of intersection between the terminal side of the angle and the Unit Circle.

• The x-coordinate of the point is equal to the cosine of the angle.

• The y-coordinate of the point is equal to the sine of the angle.

• To find the tangent of an angle you take the y-coordinate/x-coordinate.