Find the center and the radius of the circle.
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A)(0, 0), r = 81
B)(0, 0), r = 9
C)(0, 9), r = 81
D)(9, 9), r = 81

Question

Find the center and the radius of the circle.
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A)(0, 0), r = 81 
B)(0, 0), r = 9 
C)(0, 9), r = 81 
D)(9, 9), r = 81

Quizplus · Accepted Answer

The center of the circle is at (0,0) since it passes through the origin of the coordinate plane. To find the radius, we can use the distance formula between the center (0,0) and any point on the circle, such as (9,0).

r = sqrt((9-0)^2 + (0-0)^2) = 9.

Therefore, the correct answer is B. There is no visible center or radius marked on the diagram, but we can see that the circle passes through the points (-9,0), (0,-9), (9,0), and (0,9) which are all equidistant from the origin (0,0). Therefore, the center is at (0,0) and the radius is the distance from the origin to one of these points, which is 9. Choice B matches these values.

Find the Center and the Radius of the Circle