Horizontal lines run left to right, parallel to the horizon, with slope 0 and equation y = k. Vertical lines run top to bottom, perpendicular to the horizon, with undefined slope and equation x = k.

Click to see a step-by-step slideshow. STEP 1: Use the ruler to draw a vertical line, then draw a horizontal line directly from the end of the vertical line. ...rearrange the cubes so you have six ...