Question 735446
Multiply by the conjugate of the denominator over itself.  The conjugate of a+b is a-b.  Any value over itself = 1.  So you're just multiplying by one and thus keeping the same value.<P>
sin x / (1 - cos x) * (1+cos x) / (1+cos x) = sin x(1+cos x)/ (1-cos x)(1+cos x) = sin x(1+cos x)/ 1 - cos^2 x<P>
Remember that sin^2 x + cos^2 x = 1 and thus 1-cos^2 x = sin^2 x<P>
sin x(1+cos x)/ 1 - cos^2 x = sin x (1+cos x) / sin^2 x = (1+cos x) /  sin x
<P>Hope the solution helped.  Sometimes you need more than a solution.  Contact fcabanski@hotmail.com for online, private tutoring, or personalized problem solving (quick for groups of problems.)