In this demonstration, it is possible to change the positions of the two vectors, A, colored red, and C, colored white, by typing in the coordinates for each vector (in the form (x-coordinate, y-coordinate)) in the appropriate textbox and pressing enter. The line given by A + tC, with t going from -1 to the variable t0, is shown in green. The point A + t0C is also shown. To show the position vector for this point, use the second checkbox in the control window. The arrow buttons in the control window change the value of t0.