Question

The center of a circle is located at C(4,9). Its circumference is 36*pi.

What is the DIAMETER of the circle described above?

What is the RADIUS of the circle described above? *

Write the equation of the circle described above.

Answer 1

Diameter = 36

Radius = 18

Equation is (x - 4)² + (y - 9)² = 18²

Explanation:

circumference = πd

36π = πd

divide both sides by π

d = 36

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Radius = d/2

r = 36/2 = 18

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Standard form is

(x - h)² - (y - k)² = r²

(h, k) is the center and r is the radius

Using (h, k) = (4, 9) and r = 18

(x - 4)² + (y - 9)² = 18²