How do you convert x^2 -12y-36=0x212y36=0 to polar form?

1 Answer
Nov 20, 2017

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

Explanation:

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Remembering that an x,y coordinate can be represented by a right triangle with angle theta and hypotenuse r, we can derive that x=rcosthetax=rcosθ and y=rsinthetay=rsinθ.

Substituting these into your equation leaves the result
r^2cos^2theta-12rsintheta-36=0r2cos2θ12rsinθ36=0

This is a quadratic expression in r, so use the quadratic formula to solve for r
r=(12sintheta+-sqrt(12^2sin^2theta+4*36*cos^2theta))/(2cos^2theta)r=12sinθ±122sin2θ+436cos2θ2cos2θ
r=(12sintheta+-sqrt(12^2sin^2theta+-12^2cos^2theta))/(2cos^2theta)r=12sinθ±122sin2θ±122cos2θ2cos2θ
r=(12sintheta+-12)/(2cos^2theta)r=12sinθ±122cos2θ

Therefore,
r=(6sintheta+-6)/cos^2thetar=6sinθ±6cos2θ

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