Question

3. Which of the following equations has a center of (-4,7) and a diameter of 18?

(1) (x+4)*+(y – 7)' =3
(2) (x+4)* +(y-7)= 324
(3) (x+4)*+(y-7)=9
(4) (x+4)*+(y-7)* = 81

Answer 1

option 4

Explanation:

The equation of a circle in standard form is

(x - h)² + (y - k)² = r²

where (h, k) are the coordinates of the centre and r is the radius

Here (h, k) = (- 4, 7) and r = 18 ÷ 2 = 9 , then

(x - (- 4) )² + (y - 7)² = 9² , that is

(x + 4)² + (y - 7)² = 81