SOLUTION: Please help me with this equation. I have to use Trig. Identities to solve it and i can't seem to find how to subtract the two fractions. Could you show me how to get there? {{{ ((

Question 176514: Please help me with this equation. I have to use Trig. Identities to solve it and i can't seem to find how to subtract the two fractions. Could you show me how to get there?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!

((sin(a))/(1+sin(a))) - ((sin(a))/(1-sin(a))
least common denominator: (1+sin(a))(1-sin(a)) = 1- sin^2(a) = cos^2(a)
Rewrite each fraction with lcd as its denominator:
= [(sin(a))(1- sin(a)]/lcd - [(sin(a))(1 + sin(a))]/lcd
Combine the humerators over the lcd:
= [sin(a) - sin^2(a) - sin(a) -sin^2(a)]/cd
= [-2sin^2(a)]/lcd
= [-2sin^2(a)]/cos^2(a) = -2tan^2(a)
===========================================
Cheers,
Stan H.
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