Compute using Trig Identities 2

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

In this lesson, we learn how to use trig identities to make computations. Specifically, we are given the cosine of A and are asked to find the sine of 2A and the cosine of A over 2. The problem is solved by drawing a picture and using the formula for the sine of 2A, which is 2 sine A cosine A. We also use a formula for the cosine of A over 2 and solve a complex fraction to find the answer. This lesson provides helpful examples for using trig identities to solve problems.

Lesson Description:

Using Trig Identities to make computations.

More free YouTube videos by Julie Harland are organized at http://yourmathgal.com

Questions answered by this video:
• How do you make computations using trig identities?
• If cosA = 12/13 and 270 < A < 360, what are sin(2A), cos(A/2)?
• How do you find sin(2A) and cos(A/2) if you know cosA?
• Staff Review

• Currently 4.0/5 Stars.
This lesson shows how to compute cos(A/2) and sin(2A) of an angle if you know the value of cos of the angle. All steps involved in making the computations are shown and explained very clearly in this lesson. Check out the other lessons in this series for more example problems.