Proving tan2A = 2tanA/1-tan^2A: A Trig Identity Example

[TheRedDevil18]

Homework Statement

Prove the following:

tan2A=2tanA/1-tan^2A

Homework Equations

The Attempt at a Solution

Took the right hand side:

=2(sinA/cosA) / 1-(sin^2A/cos^2A)
=2sinA/cosA /cos^2A-sin^2A/cos^2A
=2sinA/cos2A /cosA/1

Dont know what to do next?

 

[Dick]

Homework Statement

Prove the following:

tan2A=2tanA/1-tan^2A

Homework Equations

The Attempt at a Solution

Took the right hand side:

=2(sinA/cosA) / 1-(sin^2A/cos^2A)
=2sinA/cosA /cos^2A-sin^2A/cos^2A
=2sinA/cos2A /cosA/1

Dont know what to do next?

What's an identity for sin(2A)? And I hope 2sinA/cos2A /cosA/1 means (2sin(A))/(cos(2A)/cos(A)) what you've written is not at all clear.