# Math Help - Trigonometric Expressions

1. ## Trigonometric Expressions

Hey guys I need some help with these two different equations. It is to simplify the expressions:

Equation 1:

9sinx/cos^2x * cosxsinx-3cosx/sin^2x-9

and the second equation is:

sin^4xcosx/cos^4xsinx

2. ## Re: Trigonometric Expressions

Hello, DjNito!

These require basic Algebra (factoring and reducing).

These are not equations . . . they are expressions.
Be precise.

$\frac{9\sin x}{\cos^2\!x}\cdot \frac{\cos x\sin x - 3\cos x}{\sin^2\!x - 9}$

Factor: . $\frac{9\sin x}{\cos^2\!x}\cdot \frac{\cos x(\sin x - 3)}{(\sin x - 3)(\sin x + 3)}$

Reduce: . $\frac{9\sin x}{\cos x(\sin x + 3)}$

$\frac{\sin^4\!x\cos x}{\cos^4\!x\sin x}$

Reduce: . $\frac{\sin^4x\cos x}{\sin x\cos^4\!x} \;=\;\frac{\sin^3\!x}{\cos^3\!x}$

Simplify: . $\left(\frac{\sin x}{\cos x}\right)^3 \;=\;\tan^3\!x$