Convert r=?+cos(3?) to rectangular coordinates

Question

Convert r=θ+cos(3θ) from polar coordinates to rectangular coordinates.

Answer 1

r =?cos(3)

x = rcos3= .14r, y = rsin3 = -.99r

r=sqr(x^2 +y^2) =sqr( r^2(cos^2(x) + sin^2(x)) = ?cos(3)

x = sqr(x^2 + y^2)cos3= about 1/.14) = about 1.823

y = rsin3 = r(sqr(1- cos^2(3))= about .99