develop identity? trigonometry?

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Develop the identity for tan 2A by using the identities for sin 2A and cos 2A.

Guest May 19, 2014

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Best Answer

+118724

+8

I've already lost the working for this once. But I will try again.

$$tan(2A)\\\\$$

$$=\frac{sin(2A)}{Cos(2A)}\\\\$$

$$=\frac{2sinAcosA}{Cos^2A-Sin^2A}\\\\$$

$$=\dfrac{\frac{2sinAcosA}{Cos^2A}}{\frac{Cos^2A-Sin^2A}{Cos^2A}}\\\\$$

$$=\dfrac{2tanA}{1-tan^2A}\\\\$$

There you go!

Melody May 20, 2014

2⁺⁰ Answers

+3502

+3

find tan2A by using the numbers found in sin2A and cos2A and add them

zegroes May 19, 2014

+118724

+8

Best Answer

I've already lost the working for this once. But I will try again.

$$tan(2A)\\\\$$

$$=\frac{sin(2A)}{Cos(2A)}\\\\$$

$$=\frac{2sinAcosA}{Cos^2A-Sin^2A}\\\\$$

$$=\dfrac{\frac{2sinAcosA}{Cos^2A}}{\frac{Cos^2A-Sin^2A}{Cos^2A}}\\\\$$

$$=\dfrac{2tanA}{1-tan^2A}\\\\$$

There you go!

Melody May 20, 2014

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