**Title:** Unit Circle - Special Angles - Just Know One

**Description:**
This lesson will demonstrate that in order to find the coordinates of the special angles on the unit circle, students will need a knowledge of the first quadrant angles only. Students will use special right triangle relationships for 30° - 60° -90° or 45° - 45° - 90° triangles to find the first quadrant coordinate values. These values will then be reflected across the x- and y-axis to locate the coordinates in the remaining quadrants. Students will also convert the angle measurements from units in degrees to units in radians. They will become familiar with finding angles in the quadrants by using reference angles (π-x, π+x. 2π-x).
This lesson results from the ALEX Resource Gap Project.
**Standard(s): **

[MA2015] PRE (9-12) 29: (+) Use special triangles to determine geometrically the values of sine, cosine, and tangent for ^{π}/_{3}, ^{π}/_{4}, and ^{π}/_{6}, and use the unit circle to express the values of sine, cosine, and tangent for π - *x*,
π + *x*, and 2π - *x* in terms of their values for *x*, where *x* is any real number. [F-TF3]

**Subject:**Mathematics (9 - 12)

**Title:**Unit Circle - Special Angles - Just Know One

**Description:**This lesson will demonstrate that in order to find the coordinates of the special angles on the unit circle, students will need a knowledge of the first quadrant angles only. Students will use special right triangle relationships for 30° - 60° -90° or 45° - 45° - 90° triangles to find the first quadrant coordinate values. These values will then be reflected across the x- and y-axis to locate the coordinates in the remaining quadrants. Students will also convert the angle measurements from units in degrees to units in radians. They will become familiar with finding angles in the quadrants by using reference angles (π-x, π+x. 2π-x). This lesson results from the ALEX Resource Gap Project.