how do you write the equation of a circle with given center and radius

Question

anonymous · Answer

(x-a)^2 + (y-b)^2 = r^2

Where r = radius, (a,b) = centre co-ordinates

anonymous · Answer

thanks can you show me an example

anonymous · Answer

(x-2)^2 + (y+3)^2 = 25

Is a circle, centre (2,-3), radius 5

anonymous · Answer

(x^2-4x+4)+(y^2+6x+9)=25
what next!

anonymous · Answer

6x most be 6y

anonymous · Answer

You could bring all the constants, on to the right and side, but the form I gave it in in generally what is needed, and the simplest (if you want cartesian, that is)

anonymous · Answer

You just have to factor those two terms and  you will get it back into the above form

anonymous · Answer

OK. well I'm a cape student but my teacher is holding back and the time is going so im going ahead by my self

anonymous · Answer

That sounds like fun.

anonymous · Answer

yea its fun but difficult at times