Conversion - Polar and Cartesian Coordinates

Refer figure above , from trigonometry note that cos θ = x / r so that x = r cos θ. Similarly sinθ = y / r , so that y = r sin θ. 

Hence , if we know the polar coordinates of a point (r , θ) , we can find its cartesian coordinates. 

Alternatively , using Pythagoras theorem , we note that r = √(x²+y²).Further tanθ = y/x , so that θ=tan^-1 (y/x) 

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