Derive Tangent of Sum and Examples

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Taught by YourMathGal
  • Currently 4.0/5 Stars.
2051 views | 1 rating
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Lesson Summary:

In this lesson, Julie Harland shows how to derive the identity for the tangent of the sum and difference of angles or real numbers. She explains how to rewrite the tangent in terms of sine and cosine, and then uses those identities to derive the formula. She provides an example of applying the formula to find the tangent of a sum when given the tangents of two angles. She also explains how to apply the formula to find the tangent of a difference when given the tangents of two angles. Check out the full video on yourmathgal.com for more information.

Lesson Description:

This video derives the identity for the tangent of the sum and difference of angles (or real numbers), and provides an example using the identity if you know the tangents of two angles, but not their sum.

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

Questions answered by this video:
  • What are the formulas for the tangent of a sum or difference of angles?
  • What is the trig identity for tan(A + B)?
  • How can you derive the formula for the tan(A + B)?
  • How can you figure out tan(30 + 30) using the tangent of an angle sum identity?
  • What is the trig identity for tan(A - B)?
  • How can you derive the formula for the tan(A - B)?
  • How can you use the tangent angle sum and difference formulas to solve triangle problems?
  • Staff Review

    • Currently 4.0/5 Stars.
    This lesson does a great job of explaining where the formula for the tangent of a sum or difference of angles comes from and how to derive that formula. All steps and parts of the derivation are shown. The formula is then used to solve some example problems.