Question 242299
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The equation of a circle with center *[tex \Large \left(h,k\right)] and radius *[tex \Large r] is


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ (x - h)^2 + (y - k)^2 = r^2]


You already have the center given to you, so all you need is the radius.  Since a circle is the locus of points equidistant from a point called the center, all you need is the distance from the center to the given point.  Reach in the tool box and take out the Distance Formula:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ d^2\ =\ r^2\ =\ (x_1\ -\ x_2)^2\ +\ (y_1\ -\ y_2)^2]


Where *[tex \Large \left(x_1,y_1\right)] and *[tex \Large \left(x_2,y_2\right)] are the coordinates of the given point and the center.


Calculate the radius squared, then substitute *[tex \Large r^2], *[tex \Large h], and *[tex \Large k] into the general equation to get your specific equation.  Remember to pay close attention to the signs.



John
*[tex \LARGE e^{i\pi} + 1 = 0]
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