# Math Help - trig reduction, where did the negative sign come from?

1. ## trig reduction, where did the negative sign come from?

we cancel (cos x - sin x) in the numerator and denominator to get 1/(cos x)

Why is it -1?

2. ## Re: trig reduction, where did the negative sign come from?

$\cos(x)-\sin(x)=-(\sin(x)-\cos(x))$

Then after dividing out this factor, the -1 is left in the numerator.

3. ## Re: trig reduction, where did the negative sign come from?

Originally Posted by kingsolomonsgrave

we cancel (cos x - sin x) in the numerator and denominator to get 1/(cos x)

Why is it -1?
Algebra Just factor a -1 out of the numerator

$\frac{a-b}{b-a}=\frac{-1(b-a)}{(b-a)}=-1$