#### Answer

$\tan^2 \beta$

#### Work Step by Step

$\frac{\sin\beta\tan\beta}{\cos \beta}$
$=\frac{\sin\beta*\frac{\sin\beta}{cos \beta}}{\cos \beta}$
$=\frac{\frac{\sin^2\beta}{\cos\beta}}{\cos \beta}$
$=\frac{\sin^2\beta}{\cos^2\beta}$
$=(\frac{\sin\beta}{\cos \beta})^2$
$=\tan^2 \beta$