You need to think of that equation in terms of the classic definition of a circle:
(x - a)2 + (y - b)2 = r2
where a and b are the center of the circle, x and y are any point on it's circumference, and r is it's radius.
In the case of the circle you're looking at:
x2 + y2 = 16
You can re-express it like this:
(x - 0)2 + (y - 0)2 = 42
So that circle has a center at the point (0, 0), and a radius of 4.
Chat with our AI personalities
(x-3)2+y2=144
x2 + y2= 16
The center of the circle is at (0, 0) and its radius is the square root of 1 which is 1
The inner circle is x2 + y2 = 4. The radius of the inner circle is the square root of 4, which is 2. To find the radius of the outer circle, multiply 2 times 4. The radius of the outer circle is 8. Square 8 (82 or 8 x 8) to find the number to put into the equation of the outer circle. This is 64. The equation for the outer circle is x2 + y2 = 64.
The equation of circle is (x−h)^2+(y−k)^2 = r^2, where h,k is the center of circle and r is the radius of circle. so, according to question center is origin and radius is 10, therefore, equation of circle is x^2 + y^2 = 100