Question 795116
Hint: 

tant = sint/cost

cos^2 t = 1-sin^2 t

Convert every trig function, in this case tant, to sint and cost.

Then, by substituting the above value for
 cos^2 t, your fraction will look like

sint(1-sin^2t)/sint

Can you finish now?

There is only one final step needed and you're done.