x^2+y^2 = 9

Question

What is the diameter of the following circle?

Answer 1

The equation for a circle is x² + y² = r²

 

r is the radius of your circle.

 

In the equation x² + y² = 9, the square of the radius is 9:

r² = 9

 

To find the radius, we just take the square root of both sides:

r = 3

 

In order to find the diameter, we just multiply the radius by 2:

diameter = 2(radius) = 2(3) = 6

 

The diameter of the circle is 6