Which equation represents a circle that contains the point (-2, 8) and has a center at (4, 0)?
(x - 4)2 + y2 = 100
(x - 4)2 + y2 = 10
x2 + (y - 4)2 = 10
x2 + (y - 4)2 = 100
Solution:
Given (-2, 8) is a point on the circle and (4, 0) is the origin of the circle
We know that the distance between centre and any point on the circle is called the radius of the circle
Radius = √{(y2 - y1)2 + (x2 - x1)2}[Using the distance formula]
x1 = -2, y1 = 8, x2 = 4, y2 = 0
Radius = √{( 0 - 8)2 + (4 - (-2))2}
Radius = √{(-8)2 + (4 + 2)2}
Radius = √{64 + 36}
Radius = √100
Radius = 10
We know that the equation of circle with circle (h, k) and radius r is given as (x - h)2 +(y - k)2 = r2
Here (h, k) = (4, 0)
(x - 4)2 + (y - 0)2 = 102
(x - 4)2 + y2 = 100
x2 - 8x + 16 + y2 -100 = 0
x2 + y2 - 8x - 84 = 0
The equation of circle is x2 + y2 - 8x - 84 = 0
Which equation represents a circle that contains the point (-2, 8) and has a center at (4, 0)?
Summary:
Equation x2 + y2 - 8x - 84 = 0 represents a circle that contains the point (-2, 8) and has a center at (4, 0).
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