More Lessons for PreCalculus

Math Worksheets

Videos, worksheets, games and activities to help PreCalculus students learn about the double angle identities.

sin(2x) = 2sin(x)cos(x)

cos(2x) = cos

Double-Angle Formulas

A few examples that use double-angle formulas from trigonometry.

Double Angle Formulas :

The double angles sin(2x) and cos(2x) can be rewritten as sin(x + x) and cos(x + x).

Applying the cosine and sine addition formulas, we find that sin(2x) = 2sin(x)cos(x).

Also, cos(2x) = cos

How to use the sine and cosine addition formulas to prove the double-angle formulas.

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