Curated OER
Tangent of a Point
In this tangent instructional activity, students find the tangent of one point when given the length of the sides of a triangle. This one-page instructional activity contains ten problems.
Purple Math
Purplemath: Quadrants and Angles
Explains how to model angles in the x,y-plane, and demonstrates how to extend the concept of trig ratios to angles larger than 90 degrees.