Question

Identify the radius and the center of a circle whose equation is (x – 5)² + y² = 81.

Answer 1

Hello there,

In order to solve this problem we need to write down the original circle equation:

• (x - h)² + (y - k)² = r²

From this equation you should note that (h, k) as the center of the circle and the r being the radius.

Now let's take a look at the equation given to us:

• (x - 5)² + y² = 81

From this you know that the center of the circle is at (5, 0). As for the radius you have to take the square root of 81 which is 9.

This circle has the center at (5, 0) and the radius at 9.

Hope I helped,

Amna

Answer 2

Radius: 9
Center: (5,0)