A circle with centre C has equation x^2 + y^2 +8x -12y = 12
Recognise that the form this question is a circleRemember alternate circle equation (x + a)2 + (x + b)2 = r2Where centre of circle (-a,-b) and r is the radiusTo get the right form use complete the square(x+4)2 -16 + (y - 6)2 -36=12rearrange into (x+4)2+ (y-6)2=64using above form centre (-4,6) and radius 8
MG
