Question

Write the standard form of the equation and the general form of the equation of the circle of radius r=9 and center (h,k)=(0,0). Graph the circle.

Answer 1

The equation of the circle is x² + y² = 81, its graph is in the image at the end.

LEt's write the circle equation:

A general circle with radius R and center at the point (a, b) is written as follows:

(x - a)² + (y - b)² = R²

Here the radius is R = 9, and the center is (0, 0), then we can write the circle equation as follows:

(x - 0)² + (y - 0)² = 9²

x² + y² = 81

And the graph of this circle is in the image at the end.