# Trig Proof

• Mar 10th 2010, 07:32 PM
Brndo4u
Trig Proof
Im caught up on this proof... need some help

CosX/SecX+SinX/CscX=Sec^2X-Tan^2X
• Mar 10th 2010, 08:29 PM
Jhevon
Quote:

Originally Posted by Brndo4u
Im caught up on this proof... need some help

CosX/SecX+SinX/CscX=Sec^2X-Tan^2X

Note that the left hand side is $\displaystyle \cos^2 x + \sin^2 x = 1$

Now recall that $\displaystyle 1 + \tan^2 x = \sec^2 x$

What can you conclude?
• Mar 10th 2010, 11:40 PM
db5vry
Quote:

Originally Posted by Brndo4u
Im caught up on this proof... need some help

CosX/SecX+SinX/CscX=Sec^2X-Tan^2X

Think of $\displaystyle secx$ as $\displaystyle \frac{1}{cosx}$ and $\displaystyle cosecx$ as $\displaystyle \frac{1}{sinx}$. when you've got something like

$\displaystyle \frac{cosx}{1/cosx}$ then do you think that this could equate to $\displaystyle cos^2 x$? Does this help you for the rest of the question if you can recall other identities that you need?
• Mar 11th 2010, 05:33 AM
Brndo4u
Yes, that I see what you guys are saying... I need to use the Recip ID, Which in the end will give me Sin^2 & Cos^2. That will become 1 and Sec^2 & Tan^2 will also be 1...So, 1 =1