I need help with this equation:

sin(x)cos(x)tan(x)=1-cos^2(x)

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- Apr 24th 2010, 07:51 PMmarekdSimple Trig Identity - help
I need help with this equation:

sin(x)cos(x)tan(x)=1-cos^2(x) - Apr 24th 2010, 07:58 PMmathaddict
- Apr 24th 2010, 07:58 PMmybrohshi5
Hi :)

substitute $\displaystyle \frac{sinx}{cosx} $ for tanx.

This will give you

$\displaystyle sinx*cosx*\frac{sinx}{cosx}= 1 - cos^2x $

as you can see the cosx will cancel on the left side of the equal sign.

This leaves you with

$\displaystyle sin^2x = 1 - cos^2x $

and you know the trig identity of $\displaystyle sin^2x + cos^2x = 1 $

Does that clear everything up for you? - Apr 24th 2010, 08:05 PMmarekd
Helps a lot. Thanks you guys