Trig Proof 9

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Taught by YourMathGal
  • Currently 4.0/5 Stars.
1318 views | 1 rating
Part of video series
Meets NCTM Standards:
Lesson Summary:

In this lesson, Julie Harland, aka Your Math Gal, walks us through two trig proofs using all of the basic identities up through half-angle identities. By verifying the given identities, she shows how to use formulas like double-angle identities, and how to recognize patterns to simplify expressions. By the end of the lesson, you'll have gained a solid understanding of the trig identities and their uses.

Lesson Description:

Two more trig proofs shown and explained.

More free YouTube videos by Julie Harland are organized at

Questions answered by this video:
  • How do you verify trig identities?
  • How do you prove that sin2x/2sinx = cos^2(x/2) - sin^2(x/2)?
  • How do you prove that tan(x/2) = cscx - cotx?
  • Staff Review

    • Currently 4.0/5 Stars.
    This trig proof lesson shows how to prove two different trig identities by using your knowledge of basic trig identities. All steps involved in proving the identities are shown and explained. The goal is to get the two sides of the equal sign to look like each other.