the points A(1;1),B(5;-1)and C(3;5) are the vertices of a triangle and AD bisects BC.Find the coordinates of D.

since AD bisects BC, point D is therefore the midpoint of B and C. recall that the formula for midpoint is given by

MP = ( (x1 + x2)/2 , (y1 + y2)/2 )
where
(x1,y1) and (x2,y2) = coordinates of B and C
substituting,
D = ( (5+3)/2 , (-1+5)/2 )
D = ( 8/2 , 4/2 )
D = (4, 2)

hope this helps~ :)