How to converting rectangular equations into polar equations

 
 
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Three formulas for converting between rectangular and polar equations

To convert rectangular equations to polar equations, we’ll use the following conversion formulas.

???x=r\cos{\theta}???

???y=r\sin{\theta}???

???r^2=x^2+y^2???

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How to convert an equation from rectangular coordinates to polar coordinates


 
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An example of converting a rectangular equation into polar coordinates

Example

Convert the rectangular equation to a polar equation.

???x^2-3x+y^2+2y=0???

Use ???r^2=x^2+y^2???.

???x^2+y^2-3x+2y=0???

???r^2-3x+2y=0???

To convert rectangular equations to polar equations, we’ll use three formulas.

Use ???x=r\cos{\theta}??? and ???y=r\sin{\theta}???.

???r^2-3r\cos{\theta}+2r\sin{\theta}=0???

???r^2=3r\cos{\theta}-2r\sin{\theta}???

???r=3\cos{\theta}-2\sin{\theta}???

Once we’ve eliminated all ???x??? and ???y??? variables, and replaced them with ???r??? and ???\theta??? variables, we’re done with the conversion.

 
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