I have to express y = 6x^2 in this fashion. here is my work.

y = r sin(theta) = 6x^2

x = r cos(theta) -> x^2 = r^2*(cos(theta))^2

rsin(theta) = 6x^2

rsin(theta) = 6( r^2) (cos(theta))^2

divide both by r...

sin(theta) = 6r (cos(theta))^2

divided the (cos(theta))^2 and the 6 to leave r alone...

(tan(theta)sec(theta))/6 = r

This is the part where i got lost, how do you find theta in this situation?