Parallelogram with coordinates

[Physicsissuef]

Homework Statement

Parallelogram ABCD is given, with A(2,4), B(5,7), C(12,8). Find the coordinates of D(x,y).

Homework Equations

The Attempt at a Solution

Sorry but, I don't have any idea.

 

[sutupidmath]

here it is a hint, although you haven't shown any work at all! do u know how to find the end points C(x2,y2) of a segment if you are given the first point say A(x1,y1), and another point in the segment say B(x,y), and a ratio, say k. ? well the formula is

x=(x1+kx2)/(1+k), same for y.
in your problem, you probably know that the diagonals of a regular paralelogram bisect each other.. so what u have to do is first find the coordinates of the point where the diagonals bisect each other, and then you will end up with an idenitcal problem that i explained above!

 

[Physicsissuef]

here it is a hint, although you haven't shown any work at all! do u know how to find the end points C(x2,y2) of a segment if you are given the first point say A(x1,y1), and another point in the segment say B(x,y), and a ratio, say k. ? well the formula is

x=(x1+kx2)/(1+k), same for y.
in your problem, you probably know that the diagonals of a regular paralelogram bisect each other.. so what u have to do is first find the coordinates of the point where the diagonals bisect each other, and then you will end up with an idenitcal problem that i explained above!

Thank you very much. It helped. D(9,5)

 

[sutupidmath]

It looks fine, although i personally haven't checked it!