View Full Version : How do you prove
renagirl99
Jul 12, 2010, 09:46 AM
Can someone help me verify this trig identity?
(sin(x))/(1-cos(x))-(sin(x)cos(x))/(1+cos(x))=csc(x)(1+cos^2(x))
galactus
Jul 12, 2010, 10:28 AM
O I appluad you on your use of grouping symbols. Few do that when they post a problem.
\frac{sin(x)}{1-cos(x)}-\frac{sin(x)cos(x)}{1+cos(x)}
Cross multiply and simplify:
\frac{sin(x)+sin(x)cos^{2}(x)}{1-cos^{2}(x)}
\frac{sin(x)(1+cos^{2}(x))}{sin^{2}(x)}
\frac{1+cos^{2}(x)}{sin(x)}
csc(x)(1+cos^{2}(x))
renagirl99
Jul 12, 2010, 11:03 AM
how did you get (1+cos^2(x)) in the third step?
galactus
Jul 13, 2010, 06:19 AM
Factor out the sin(x) in the numerator.