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how to find Circle equation?

how do you determine the equation of a circle that has diameter endpoints (-2,7) and (2,-7)

the equation format is r^2 = x^2 + y^2

thanks

Answers (3)

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aa11424861 profile image
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mqgzlgewaa profile image

First, find the midpoint between the 2 points:

x = (-2 + 2) / 2 = 0/2 = 0

y = (7 - 7) / 2 = 0/2 = 0

So, the circle is centered at (0 , 0)

The radius is the distance from the center to any point on the surface of the circle

(-2 - 0)^2 + (7 - 0)^2 = r^2

4 + 49 = r^2

53 = r^2

(x - 0)^2 + (y - 0)^2 = 53

x^2 + y^2 = 53

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ynnzy5zjaa profile image

it is....you can plot points, or just memorize the formula. -_-

Reference: Ting ting Li gave me credit for embarrassing her wall.