The equation of the circle whose center is at the origin and whose diameter is 12.5 is x²+y²=39.0625
The formula for finding the equation of a circle is expressed as:
(x-a)² + (y - b)² = r²
where
(a, b) is the centre
r is the radius
Given the following
(a, b) = (0, 0)
r = 12.5/2 = 6.25
Substitute
(x-0)² + (y - 0)² = 6.25²
x²+y²=39.0625
Hence the equation of the circle whose center is at the origin and whose diameter is 12.5 is x²+y²=39.0625
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