How do you convert 4=(x+8)^2+(y-6)^24=(x+8)2+(y6)2 into polar form?

1 Answer
May 23, 2016

Polar form is r^2+4r(4costheta-3sintheta)+96=0r2+4r(4cosθ3sinθ)+96=0

Explanation:

A Cartesian point (x,y)(x,y) in polar form is (r,theta)(r,θ), where

x=rcosthetax=rcosθ and y=rsinthetay=rsinθ and hence

x^2+y^2=r^2cos^2theta+r^2sin^2theta=r^2x2+y2=r2cos2θ+r2sin2θ=r2

Hence 4=(x+8)^2+(y-6)^24=(x+8)2+(y6)2 can be written as

(rcostheta+8)^2+(rsintheta-6)^2=4(rcosθ+8)2+(rsinθ6)2=4

or r^2cos^2theta+16rcostheta+64+r^2sin^2theta-12rsintheta+36=4r2cos2θ+16rcosθ+64+r2sin2θ12rsinθ+36=4

or r^2+r(16costheta-12sintheta)+64+36-4=0r2+r(16cosθ12sinθ)+64+364=0

or r^2+4r(4costheta-3sintheta)+96=0r2+4r(4cosθ3sinθ)+96=0