The general equation of a circle in the Cartesian coordinate system is (x-a)^{2} + (y-b)^{2} = r^{2}. The point (a,b) represents the center of the circle and the value of r represents the radius of the circle.
Continue ReadingMathematicians can also describe a circle in the polar coordinate system by the general equation a^{2} = r^{2} + 2rRcos(theta-phi) + R^{2}, where the point (R,phi) represents the center of the circle in polar coordinates and the value of a represents the radius of the circle. When solved for the variable r, this equation can be rewritten as r = Rcos(theta-phi) + (a^{2}-(sin(theta-phi))^{2})^1/2.
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