a)Find the equation of the circumference that crosses:
M(-1,1), N(8,-2), S(0,4).

b) verify that the line a) 3x+4y+9=0 is tangent to that circumference.

Question

a)Find the equation of the circumference that crosses:
M(-1,1), N(8,-2), S(0,4).

b) verify that the line a) 3x+4y+9=0 is tangent to that circumference.

owlcoffee · Answer

@dumbcow 
@amistre64

anonymous · Answer

All points on the circumference have to be the same distance from the origin.  Use the distance formula and let the center be at (x, y).  solve for x and y.

dumbcow · Answer

well a circle is defined as
$$(x-h)^{2} +(y-k)^{2} = r^{2}$$
plug in the 3 points to get system of 3 equations with 3 unknowns (h,k,r)

anonymous · Answer

You might have to rework slightly to get linear equations but @dumbcow has hit it on the nose.

owlcoffee · Answer

I do believe they would work better if i wrote them in general formula :P 
but a system is a good idea.