View Full Version : Cos/1+sin + cos/1-sin =2 sec
kathlyniciousz
Jan 30, 2011, 03:20 AM
Please help me to answer this. Thank you! :) LOVE.love!
galactus
Jan 30, 2011, 05:01 AM
\frac{cos(x)}{1+sin(x)}+\frac{cos(x)}{1-sin(x)}=2sec(x)
Like when adding any fraction, get the denominators the same.
\frac{(1-sin(x))cos(x)}{(1-sin(x))(1+sin(x))}+\frac{cos(x)(1+sin(x))}{(1-sin(x))(1+sin(x))}
\frac{(1-sin(x))cos(x)+cos(x)(1+sin(x))}{(1-sin(x))(1+sin(x))}
Notice the denominator is the factored form of the difference of two squares, and the numerator simplifies to 2cos(x):
\frac{2cos(x)}{1-sin^{2}(x)}
\frac{2cos(x)}{cos^{2}(x)}
\frac{2}{cos(x)}
2sec(x)
kathlyniciousz
Jan 30, 2011, 01:10 PM
Thank you so much GALACTUS!
kathlyniciousz
Jan 30, 2011, 01:12 PM
Anyway, I was wrong. I should put it how to prove that. :/ thank you so much for responding!