# help on trig identity containing fractions and a one

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• November 3rd 2009, 06:55 PM
sifaka
help on trig identity containing fractions and a one
$\frac{\frac{cos^2B}{sin^2B}-cos^2B}{\frac{1}{sin^2B}-1}=?cos^2B$
My real problems is that I can't see what to do with the expression containing both fractions and an integer, divided by another expression containing a fraction and an integer. Can you point me in the right direction?
~sif
• November 3rd 2009, 07:21 PM
pickslides
$1 = \sin^2(B)+\cos^2(B)$

That will take care of the integer.