# Fundamental Trig Identities

I just don't get this stuff. I've been trying on my own with the book. Also, is there a better way to post this?

1. Homework Statement
tanx 1 + secx
_________ + _________ = 2csc x
1 + secx tanx
I need to prove that this side equals the other.

2. Homework Equations

http://users.rcn.com/mwhitney.massed/trigresources/trig-reference.html [Broken]
^^The reference I was using.

3. The Attempt at a Solution
tanx(tanx) 1 + secx(1 + secx)
_________ + _________ = 2csc x
1 + secx(tanx) tanx(1 + secx)

tan2 x 1 + 2secx + sec2x
________________ + _________________
1 + secx(tanx) (tanx)1 + secx

tan2x + 1 + 2secx + sec2x
_________________________
1 + cos 1/x(tanx)

sec2x + 2cos 1/x + sec2x
_________________________
1 + cos 1/x(tanx)

This is as far as I get before I get lost.

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Integral
Staff Emeritus
Gold Member
First look at https://www.physicsforums.com/showthread.php?t=8997"thread to learn how to use LaTex. With that you can do this:

$$\frac { \tan x } { 1 + \sec x} + \frac {1 + \sec x} {\tan x} = 2 \csc x$$

Now, try multipling the top and bottom of the first term on the left by $$1 - \sec x$$

BTW: Just click on my equations to see what I typed to produce them.

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