Please answer the question with qu 1a equation equal to r

Question 1a) Convert the Cartesian equation (x^2 +y^2-1)^2 +4y^\\2-1 =0 to polar coordinates. (make it as an equation equal to r) 1b) Use a trigonometric identity to show that the polar equation can be simplified as r^2 = 2 cos 20. Explain why all the solutions of the original equation are still solutions of this equation (noting that you have probably divided both sides by rA2)