here's what you want to do. first, find . how? just plug in all the values and solve.

we know and you found

simplify that, and plug in when done. or you can just plug it in now and calculate the result, it's up to you

now, when ,

so the point we are concerned with is

now we must change this coordinate to Cartesian coordinates:

recall, to go from Polar coordinates to Cartesian coordinates , we use the fact that:

and

use those equations to find the point

now, finally, use the point slope form to get the equation of the tangent line.

using and as the point you found just above, we have by the point slope form:

plug in the values and solve for and that's your line