Simple Trig Identity

**marekd** · April 24th 2010, 07:51 PM

I need help with this equation:

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

**mathaddict** · April 24th 2010, 07:58 PM

Originally Posted by marekd

I need help with this equation:

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

hi

some hints ,

tan x = sin x/cos x

sin^2 x + cos^2 x=1

**mybrohshi5** · April 24th 2010, 07:58 PM

Hi

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

This will give you

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

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

This leaves you with

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

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

Does that clear everything up for you?

**marekd** · April 24th 2010, 08:05 PM

Helps a lot. Thanks you guys

Thread: Simple Trig Identity - help

LinkBack

Thread Tools

Display

Simple Trig Identity - help

Similar Math Help Forum Discussions

Simple Big-O identity

[SOLVED] Another simple trig identity

Simple Trig Identity Question

[SOLVED] Help with simple Trig Identity Q

Search Tags