# The small circle has equation #x^(2)+y^(2)-2x-4y-4=0#. The great circle equation have the same radius with the diameter of the small circle is ...?

##### 1 Answer

If I understand your question correctly, the large circle has a radius of 6. If the two circles share the same center, the equation of the large circle is

#### Explanation:

Get the equation of the circle from general form to standard form by completing the two squares:

Rearrange terms, move constant to other side of the equation:

Complete the square for the

Simplify

This is the standard form of the circle.