Answer:
10
Explanation:
Standard form for a circle is
(x - h)² + (y - k)² = r²
where (h, k) is the center and r is the radius
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x² + y² - 18x + 24y = -200
Rearrange
(x² - 18x) + (y² + 24y) = -200
Complete the square for x
(x - 9)² + (y² + 24y) = -200 + (-9)²
Complete the sqaure for y
(x - 9)² + (y + 12)² = -200 + (-9)² + 12²
(x - 9)² + (y + 12)² = 25
Now the equation is in standard form
r² = 25
r = 5
Therefor Diameter = 10