Find coordinates of a point on a square I have been given the following question.

I've got no problem calculating the area of the square. However, I don't understand how to find points $A$ or $D$ in order to identify the equation of the line $AD$, so that I can then get the coordinates of $S$ by plugging in the $y$ value.

Furthermore, is there an equation where you can input distance, gradient &amp; the coordinates of one point to output the coordinates of another point?

Thanks.
it is easy to find the line AB since it is perpendicular to CB, you know the length of AB so you find A, than the Line parallel to CB cuts the x- Achse in S
next question: if you use vectors to describe lines  and the directionvektor a unit vector, 
in your first question you also could find A bei adding the Vektor BA to A.
I think that the triangle SAB and EBC are the same where E is intersection of y-axes and AB. You can easily compute the length of [EC]. After you need only make a substraction.