What is the equation of a circle centered at the origin with radius 13?

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1 Answer
Jul 2, 2016

It is #x^2+y^2-169=0#.

Explanation:

The circle you are looking fore is composed by all the points with a distance from the origin of #13#/ The distance of a point from the center is

#d=sqrt(x^2+y^2)# and this distance has to be #13#, so

#13=sqrt(x^2+y^2)# and to obtain the equation we can do the square

#13^2=x^2+y^2# and the final equation is

#x^2+y^2-169=0#.