Write the equation in standard form for a circle with center (-8,9) and tangent to the x-axis.
the standard form of the equation of the circle is

The standard form of the equation of the circle is

Solution:

Given, a circle has center (-8, 9) and x – axis as tangent.

First, let's determine r.  

The center is 9 above the x-axis and the circle is tangent to the x-axis, so the radius r should be equal to 9.

The center moved 8 to the left, so substitute x by (x + 8).

The center moved 9 up, so substitute y by (y − 9).

You can determine these numbers by filling in the center coordinates, the outcome must be zero. [x+8=−8+8=0]

The standard equation

So, the equation becomes

Hence, standard form of the circle is

the correct answer is 828.07

the answer is c

step-by-step explanation: