Question

What is the general form of the equation for the given circle? A. x2 + y2 − 8x − 8y + 23 = 0 B. x2 + y2 − 8x − 8y + 32 = 0 C. x2 + y2 − 4x − 4y + 23 = 0 D. x2 + y2 + 4x + 4y + 9 = 0

Answer 1

The correct option is A....

Explanation:

Look at the attached picture:

A=(4,7)

B=(7,4)

The standard form of circle equation is:

(x-h)^2 +(y-k)^2 = r^2

Here h and k is the centre which is (4,4)

radius = 7-4 = 3

Now use the formula to find the answer:

(x-h)^2 +(y-k)^2 = r^2

(x - 4)^2 + (y - 4)^2 = 3^2

If we expand the formula we get:

x^2 - 8x + 16 + y^2 - 8y + 16 = 9

x^2 - 8x + y^2 - 8y + 23 = 0

Thus the correct option is A....