Note: See attached document for full lesson w/tables and handouts

**Synopsis**

Students use special right triangles and angle/arc measures to build the x and y – coordinates that correspond to sine and cosine on a unit circle.

**Main Standard**

T 2.0 Students know the definition of sine and cosine as y – and x -coordinates of points on the unit circle and are familiar with the graphs of the sine and cosine functions.

**Materials**

Compasses, Protractors, Rulers, Scientific Calculators, Blank Paper

Copies, Special Right Triangles.

**Teacher Directions**

*Warm-up*

Have students recall from Geometry how the sides of a triangle are represented in special right triangles. Have them work on activity sheet, Special Right Triangles. Students should keep this sheet to reference for the next section.

*Directed Instruction*

Pass out a blank sheet of paper. Give directions to and demonstrate the following and have students do the same on their paper.

• Draw an x/y axis in the middle of the paper.

• Draw a large circle in the middle of the paper and reference it as a unit circle, marking the x – and y -intercepts as (1, 0) and (0, 1).

• Draw a 30 angle in the first quadrant with one of its sides on the x-axis. Mark the triangle ABC (see sample).

*Group Work*

Ask them to find the coordinates of the A.

Here are some inquiry prompts you may want to use with the groups as you are walking around and as needed: (see attached doc)

Source: http://auhsdmath.pbworks.com/