Question

I really need help

What is the equation of a circle whose center is begin ordered pair negative 4 comma 6 end ordered pair and whose radius is 9 cm?

A.open parentheses x minus 4 close parentheses squared plus open parentheses y minus 6 close parentheses squared equals 81


B.open parentheses x plus 4 close parentheses squared plus open parentheses y minus 6 close parentheses squared equals 3


C.open parentheses x plus 4 close parentheses squared plus open parentheses y minus 6 close parentheses squared equals 81


D.open parentheses x minus 4 close parentheses squared plus open parentheses y plus 6 close parentheses squared equals 3

Answer 1

The answer is (C)

The equation of the circle is (x + 4)² + (y - 6)² = 81

Explanation:

* To find the equation of the circle you need to know

the center of the circle and the length of its radius

* The rule of the equation of the circle is:

(x - h)² + (y - k)² = r²

Where x and y is a general point on the circle,

h and k are the coordinates of the center of the circle

and r is the radius of the circle

∵ The center of the circle is (-4 , 6)

∵ The radius of the circle is 9

∴ (x - -4)² + (y - 6)² = 9²

∴ ( x + 4)² + (y - 6)² = 81

∴ The answer is (C)