# ALEX Lesson Plan

## Unit Circle - Special Angles - Just Know One

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This lesson provided by:
 Author: Lorie White System: Lauderdale County School: Rogers High School
General Lesson Information
 Lesson Plan ID: 35670 Title: Unit Circle - Special Angles - Just Know One Overview/Annotation: 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.
Associated Standards and Objectives
Content Standard(s):
 Mathematics MA2015 (2016) Grade: 9-12 Precalculus 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]

Local/National Standards:

Primary Learning Objective(s):

Students will identify the relationship of the sides of a 30° - 60° -90° and a 45° - 45° - 90° triangle.

Students will find the coordinates of the angles on the unit circle in quadrant I by using special right triangle relationships.

Students will convert angles in degree measurement to radian measurement.

Students will apply their knowledge of reflecting objects in the coordinate plane across the x-axis and the y-axis to find the coordinates of special angles in quadrants II, III and IV.

Students will find reference angles for special angles in quadrants II, III, IV. They will use π-x, π+x. 2π-x.