Introduction
You know how to find the length of the third side of a right triangle when the lengths of the two other sides were given, but how does a person determine the length of a side if the measure of one of the angles is given along with the length of just one of the triangle's sides?

In this set of investigations you will learn:

• the fundamental concepts behind trigonometry
• the three basic trig functions
• how to determine which trig function to use
• the domain and range of trig functions
• how to determine the missing lengths of sides of a right triangle
• how to find the measure of the angles of right triangles when the lengths of two sides of the triangle are known

Along the way, you will be given some questions with answers highlighted in white. You are encouraged to avoid the temptation to get the answers to these questions before you have had a chance to think about the answers as these will be the same questions you can expect to see at the end of this lesson.

The applets were created with the help of JavaSketchpad an add-on to The Geometer's Sketchpad published by Key Curriculum Press. Please use with up-to-date browsers that are java compatible.