How do you convert y=(x-y)^2-x^2y +xy^2 y=(xy)2x2y+xy2 into a polar equation?

1 Answer
Apr 15, 2016

0=r^2-r^2sin(2theta)-1/2 r^3costhetasin(2theta)+1/2r^3sinthetasin(2theta)-rsintheta0=r2r2sin(2θ)12r3cosθsin(2θ)+12r3sinθsin(2θ)rsinθ

Explanation:

0=x^2-2xy+y^2-x^2y+xy^2-y0=x22xy+y2x2y+xy2y

0=x^2+y^2-2xy-x^2y+xy^2-y0=x2+y22xyx2y+xy2y

use formulas:
x^2+y^2=r^2,x=rcostheta,y=rsinthetax2+y2=r2,x=rcosθ,y=rsinθ

0=r^2-2rcosthetaxxrsintheta-r^2cos^2thetaxxrsintheta+rcos thetaxxr^2sin^2theta-rsintheta0=r22rcosθ×rsinθr2cos2θ×rsinθ+rcosθ×r2sin2θrsinθ

0=r^2-2r^2sinthetacostheta-r^3sinthetacos^2theta+r^3sin^2thetacostheta-rsintheta0=r22r2sinθcosθr3sinθcos2θ+r3sin2θcosθrsinθ

0=r^2-r^2(2sinthetacostheta)-1/2 r^3costheta(2sinthetacostheta)+1/2r^3 sintheta(2sinthetacostheta)-rsintheta0=r2r2(2sinθcosθ)12r3cosθ(2sinθcosθ)+12r3sinθ(2sinθcosθ)rsinθ

0=r^2-r^2sin(2theta)-1/2 r^3costhetasin(2theta)+1/2r^3sinthetasin(2theta)-rsintheta0=r2r2sin(2θ)12r3cosθsin(2θ)+12r3sinθsin(2θ)rsinθ