7. Circles in the Coordinate Plane
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What is the standard equation of a circle?
x^2+y^2=4
In this form, ( h, k) is the center of the circle and r is its radius. Let's consider the graph of our circle.
We see that the center of the circle is ( 0, 0) and its radius is 2. This information is enough to write the equation. (x- 0)^2+(y- 0)^2= 2^2 ⇕ x^2+y^2=4