Question 569894
(sin(x)tan(x))/cos(x)


(sin(x)[sin(x)/cos(x)])/cos(x)



(sin^2(x)/cos(x))/cos(x)



(sin^2(x)/cos(x))/(cos(x)/1)



(sin^2(x)/cos(x))*(1/cos(x))



(sin^2(x)/cos^2(x))



tan^2(x)



So the entire expression simplifies to tan^2(x)