Show that the line 2x+3y=27 is a tangent to the circle with centre (4,2) and radius sqrt of 13. Find the co-ordinates of the point of contact. (Without a calculator)
The Attempt at a Solution
I have worked out that the equation of the circle is (x-4)^2 + (y-2)^2=13.
I have tryed to substitute in values of x and y from the equation of the tangent to try and work out the discriminant but I haven't been able to create an equation with just either Xs or Ys in that is easy to work out the disccriminant of without using a calculator. Please show me the method for both parts of the question.