Seriously, How to find a center of a circle ?

So everyone know's how to find the center of a square, it's extremely easy.  Draw a line from each corner diagonally and where they cross is your center.  No Big Deal..... But how the hell do you actually find the center of a circle?  sure i would just eye it and say "screw it close enough" but with the power of Google one thinks during his lunch break (me) "Seriously, how do you find the center of a circle?" 

This diagram tells you all....

Draw a (black) line across the circle and measure the half way mark and make a 90 degree perpendicular line.   

Now draw another (orange) line and repeat.  Find the half way mark, and make a 90 degree perpendicular line.  

this enough to actually find the center but if you want to make sure you've got it right, draw another (purple) line and repeat.  

BOOM ! center found..... Just blew your mind ! 

So why the hell would i want to know the center of a circle?  well.... wait for my next blog post

Teaser pic