I have a question that is confusing me.

Suppose the curve is traced by the parametric equations:

x = 3sin(t)

y = 25-6cos^2(t)-12sin(t)

At what point (x,y) on this curve is the tangent line horizontal??

I know that I need to find (dy/dt)/(dx/dt)

I think that the derivative of y is messing me up to start with.

Then I know I need to find the points for t and sub them into the x and y equations given but I am not getting the correct answers.

Can anyone help?