jetblack2479
Jun 15, 2007, 11:02 PM
I need to show working and prove that: (cosx)/(1-sinx) + (cosx)/(1+sinx) = 2Secx
galactus
Jun 16, 2007, 03:51 AM
What seems to be the trouble?
You have:
\frac{cosx}{1-sinx}+\frac{cosx}{1+sinx}
Now, the objective is to show that it is equal to 2secx.
As with any fraction, get the denominators the same. What's your LCD?:
It's (1+sinx)(1-sinx)
\frac{(1+sinx)cosx}{(1+sinx)(1-sinx)}+\frac{cosx(1-sinx)}{(1+sinx)(1-sinx)}
Now, finish up? Remember that 1-sin^{2}x=cos^{2}x