The equation of a circle, C is x^2+y^2-8x+10y+28=0

(i) Find the coords. of the centre of C and find the radius of C.

(ii)Show that the line L:2x+3y=6 is a tangent to the circle and find the coords. of the point of contact.

Please do part(ii). Anyway i have found the coords. of the pt. of contact which is (6,-2). But how to show that the line is a tangent to the circle??