Mathematics · essential
Centre and radius from general circle for JEE
Circle, conic sections: A standard form of equations of a circle, the general form of the equation of a circle, its radius and centre
Formula
\(\text{Centre}=(-g,-f),\quad r=\sqrt{g^2+f^2-c}\)
Variables: For circle \(x^2+y^2+2gx+2fy+c=0\).
Conditions: Real circle when \(g^2+f^2-c>0\).
Immediate extraction of centre and radius.