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

1 Answer
May 21, 2018

r=(costheta-sintheta)/((2-costheta)sinthetacostheta)r=cosθsinθ(2cosθ)sinθcosθ

Explanation:

y=x-2y+xy^2y=x2y+xy2
x=rcosthetax=rcosθ
y=rsinthetay=rsinθ
Thus,
rsintheta=rcostheta-2rcosthetaxxrsintheta+rcosthetaxx(rsintheta)^2rsinθ=rcosθ2rcosθ×rsinθ+rcosθ×(rsinθ)2

rsintheta=rcostheta-2r^2sinthetacostheta+r^2sin^2thetacosthetarsinθ=rcosθ2r2sinθcosθ+r2sin2θcosθ

rsintheta-rcostheta=r^2(-2sinthetacostheta+sin^2thetacostheta)rsinθrcosθ=r2(2sinθcosθ+sin2θcosθ)

r(sintheta-costheta)=r^2sinthetacostheta(-2+costheta)r(sinθcosθ)=r2sinθcosθ(2+cosθ)

r(sintheta-costheta)+r^2sinthetacostheta(2-costheta)r(sinθcosθ)+r2sinθcosθ(2cosθ)

r(sintheta-costheta+rsinthetacostheta(2-costheta))=0r(sinθcosθ+rsinθcosθ(2cosθ))=0

r=0r=0

sintheta-costheta+rsinthetacostheta(2-costheta)=0sinθcosθ+rsinθcosθ(2cosθ)=0

rsinthetacostheta(2-costheta)=costheta-sinthetarsinθcosθ(2cosθ)=cosθsinθ
r=(costheta-sintheta)/((2-costheta)sinthetacostheta)r=cosθsinθ(2cosθ)sinθcosθ