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dejalisco5 · May 14, 2008, 10:46 AM

1+sin x/cos x - cos x/sin x - 1

galactus · May 14, 2008, 10:57 AM

The trick is to make the denominators the same as if you were adding any ol' fraction.

$\frac{(sin(x)-1)}{(sin(x)-1)}\cdot\frac{(1+sin(x))}{cos(x)}-\frac{cos(x)}{(sin(x)-1)}\cdot\frac{cos(x)}{cos(x)}$

Do this and expanding, we get $\frac{sin^{2}(x)-1-cos^{2}(x)}{cos(x)(sin(x)-1)}$

But $sin^{2}(x)-1=-cos^{2}(x)$

Can you continue and whittle away at it some more?