Question

Find the equation of a circle whose center is at the origin and radius is 4.

Answer 1

Equation of Circle: (x - h)^2 + (y - k)^2 = r^2
where,
[(h,k) is the center of the circle at the origin]
r is the radius,
(h,k) = (0,0), r = 4
(x - 0)^2 + (y - 0)^2 = 4^2
x^2+y^2 = 16
the equation of the circle x2+y2 = 16

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