This is a free lesson from our course in Algebra II
This lesson covers important basics of a circle like
radius,
center etc. Further you'll learn how to identify the
key elements and graph the circles. You will find some examples with solution, and
the instructor explains all that with the help of audio, video presentation and
in own hand writing. A circle is the set of all points equidistant from a given
point and this point is called the center. The distance from
the center to a point on the circle is called the radius. When the center of the
circle is at origin (0, 0), and the radius is r, its equation is x^{2}
+ y^{2} = r^{2} and equation of circle with center
at point (h , k) is
(x  h)^{2} + (y
 k)^{2} = r^{2}.
For example, equation of circle with center (3 , 3) and radius 2 is
(x  3)^{2} +
(y  3) ^{2} = 4.
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