Lesson Materials

Lesson 7-3: Defining the Trig Functions

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The student will be able to evaluate the sine, cosine, tangent, secant, cosecant and cotangent of angles given a point on the terminal side of the angle in standard position.

  1. In the applet to the left, the measurements on the circle have been labeled as SIN, COS, TAN and COT.

  2. Drag the orange slider. This will increase and decrease the size of the triangle, keeping the same angle measures.
  3. Look at the trig ratios. Even though the sides of the triangle change measures, the ratios are always equal!
  4. Will this be true for all triangles?
  1. Explore basic trig functions. C.a.R. Activity
  2. Explore Learning

GNU: This site has an outstanding introduction to the concept of sine and cosine called "Discovering Trig." This would be a great investigation for students to go through independently or in pairs. The tutorial starts with some basic questions about trigonometry as a subject, as the students finish reading and interacting with each page they should click to go to the next page. This overview touches on the definitions of sine and cosine as well as the shapes of their graphs. GNU
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