how to move a line in perpendicular direction on xy plane?

i am trying to make a rectangle(curve) from a single curve. but to do that i need to move the lines in perpendicular direction so that i can join the end points of new and old lines together to form a right angle rectangle shape. i attempted to solve it using sin and cos maths functions in order to get the vectors but it does not seem like working. Can someone help?

maybe there is a component that can do the job?

thanks in advance =]