Posted by Anonymous on .
prove that the points (2,1) (0,2) (2,3)and (4,0) are the coordinates of vertices of a parallelogram and find the angle between its diagonals

maths plse help me.. 
Steve,
If we label the points ABCD as given, then
AB and CD have slope 3/2
AD and BC have slope 1/2
so, the sides are parallel
AC is vertical
BD has slope 1/2
so, tanθ = 2 ==> θ = 63.4°
The calculations are easier if you plot the points and draw the diagonals.