How do you convert x^2+y^2 - 2y=0x2+y22y=0 to polar form?

1 Answer
May 16, 2016

r=2sinthetar=2sinθ

Explanation:

Using the formulae that link Cartesian to Polar coordinates.

• x = rcostheta" and "y=rsinthetax=rcosθ and y=rsinθ

and substituting into the given equation

rArr(rcostheta)^2+(rsintheta)^2-2rsintheta=0(rcosθ)2+(rsinθ)22rsinθ=0

expanding brackets to obtain.

r^2cos^2theta+r^2sin^2theta=2rsinthetar2cos2θ+r2sin2θ=2rsinθ

Take out a common factor of r^2r2

rArrr^2(cos^2theta+sin^2theta)=2rsinthetar2(cos2θ+sin2θ)=2rsinθ

using the trig. identity color(red)(|bar(ul(color(white)(a/a)color(black)(cos^2theta+sin^2theta=1)color(white)(a/a)|)))

rArrr^2=2rsintheta

divide both sides by r

rArrr=2sintheta