finding triangle circumcentre with equations for the triangle sides
Posted on 2010-01-12
I'm trying to find the triangle circumcentre from the equations for the triangle sides. I don't think I'm doing it right as I can't see how to finish the question off.
To get the circumcentre I need the point of intersection of 2 perpendicular bisectors. Given the equation of the side, the gradient of the bisector is -1/m but i don;t know how to get a point on this line to then work out the equation for the line using y - y1 = m(x - x1). I could say that the midpoint of the side is ((x1 + x2)/2, (y1 + y2)/2) and this point is on the perpendicular bisector but i don't know how to put this knowledge into y - y1 = m(x - x1). There's too many different x and y variables.
Once i have got the equation for one bisector i can get the others and then solve these equations simulataneously to get the midpoint.
The equations of the triangle are
y = 3x
y + 3x = 0
3y -x +12 = 0