Trig Proof 5
In this trigonometry lesson, Julie Harland demonstrates how to verify a trig identity using basic identities and the identity for the cosine of a sum or difference. The problem is to prove that (cos(x+y))/(cosx * cosy) = 1 - tanx * tany. She shows two methods of proving the identity, one where you work on one side and simplify until it looks like the other side, and the other where you work on both sides. By the end of the lesson, you will have learned how to verify trig identities step-by-step.
We verify a Trig identity by using the basic identities and the identity for the cosine of a sum or difference. We prove that (cos(x+y))/(cosx * cosy) = 1 - tanx * tany using a trig proof.
More free YouTube videos by Julie Harland are organized at http://yourmathgal.com
- How do you verify trig identities?
- How can you prove that (cos(x+y))/(cosx * cosy) = 1 - tanx * tany
- How do you make one side of the equal sign equal the other side in a trig proof?
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Staff Review
This lesson shows how to do a trig proof by making one side of the equal sign look like the other side. All steps of the proof are shown in a way just as you would be expected to complete such a proof. This is a great trig proof tutorial.
