This video can help you make draw perpendicular lines. Just remember to find the slope of the first line using two points.

For example, (1,2) and (3,7). The slope of the line is (5/2) because, 7 - 2 = 5 and 3 - 1 = 2. Here's a video for perpendicular lines:


For parallel lines, know the slope of the original. Use the third point with the new slope. I will post something about this on Sunday.