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Circle problem.Find the center and the radius of the circle: (x - 1)^2 + (y + 3)^2 = 4.

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lillyan | Student, Undergraduate | eNoter

Posted May 25, 2011 at 1:41 AM via web

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Circle problem.

Find the center and the radius of the circle: (x - 1)^2 + (y + 3)^2 = 4.

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giorgiana1976 | College Teacher | Valedictorian

Posted May 25, 2011 at 2:27 AM (Answer #2)

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We'll write the standard equation of the circle:
(x-h)^2 + (y-k)^2 = r^2
(h,k) represent the center of the circle and r is the radius of the circle.
Comparing the given equation and the standard form, we'll get:
h = 1 , k = -3 and r = sqrt4 = 2
The center of the circle has the coordinates C(1 , -3) and the radius r = 2.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted May 25, 2011 at 2:39 AM (Answer #3)

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The standard equation of a circle with center (h, k ) and radius r is (x - h)^2 + (y - k)^2 = r^2

Here we have the equation of the circle as : (x - 1)^2 + (y + 3)^2 = 4

Comparing with the standard equation h = 1, k = -3 and r = 2

The center of the given equation is (1, -3) and the radius is 2.

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