Pre-Calculus 12 Notes

By: Gen L.

Lesson 4: Special Angles

Special Triangles, Part I

Special Triangles, Part II

Unit Circle

Reference Angles

There are 4 angles in 1 rotation that have the same reference angle. This means they have the same trigonometric ratios. 2 are positive, 2 are negative.

Reference Angle Test

Let , what are the general trig ratios for each angle with the same

Since these have the same , they are the general ratios for them.

Finding Exact Values

1. Find the quadrant.
2. Find .
3. Find the trig value.
4. Determine sign.

Exact Value Example (deg)

Find exact value of .

Exact Value Example (rad)

Find exact value of .

Exact Value Example (expr)

Find exact value of

Exact Coordinates of Points

If is at the intersection of the terminal arm and , determine exact coordinates of .

Next Lesson