View Full Version : Solving trionometric identities.
 
 americalvr
Feb 26, 2008, 05:25 PM
somebody pleease help me. :confused:  I've tried figuring out this problem and can't seem to get it. :mad: you have to verify the trig identity
 
the problem is
(cotx/cosx)+(secx/cotx)=sec2xcscx
 
 
pleeease help me.
 rockerchick_682
Feb 26, 2008, 05:36 PM
Uh it's been a while. But have you tried  converting them all to cosx and sinx? Isn't cotx cosx over sinx? And secx is 1/cosx? Well I'd try that. Keep trying to substitute all the rules in
 galactus
Feb 27, 2008, 07:51 AM
You have some bad notation. You have sec(2x) when you mean sec^{2}(x). Please use the ^ for powers.  Better yet, if you plan on posting to any extent, try learning a little LaTex. If you wish, you can click on 'quote' at the bottom of my post to see the code I used to display it. 
 
\frac{cot(x)}{cos(x)}+\frac{sec(x)}{cot(x)}=sec^{2 }(x)csc(x)
 
The previous advise was good. Convert the left side to sin and cos.
 
\frac{\frac{cos(x)}{sin(x)}}{cos(x)}+\frac{\frac{1 }{cos(x)}}{\frac{cos(x)}{sin(x)}}
 
\frac{1}{sin(x)}+\frac{sin(x)}{cos^{2}(x)}
 
Now, can you continue? A little cross multiplying and you should see it fall together.. Write back if you remain stuck.  Just remember your identities. sin^{2}(x)+cos^{2}(x)=1 may prove handy.