View.Set ("offscreenonly")
var lin1 : real
var x, y, click : int
var angle : real
loop
    mousewhere (x, y, click)
    lin1 := sqrt (x ** 2 + y ** 2)
    if x = 0 then
        angle := 90
    else
        angle := arctand (y div x) %< this is the problem
    end if
    put "x = ", x
    put "y = ", y
    put "Length of line = ", lin1
    put "Angle to x axis = ", angle
    Draw.Line (0, 0, x, y, 7)
    View.Update
    cls
end loop