You may have been wondering what happens when we have a sloped surface on an object. Here we will learn how to deal with this scenario.

First we need to really look at what happens when we view an object Orthographically. If we look at the front face of an object the side faces become a line at the edge. This means that a line can represent an edge where two surfaces meet. See how the blue, red, brown and yellow faces become lines when we look at the green face.

When we view slopes two different cases arises. The slope can become a line, just like above. In the animation below see how the purple face becomes a line.

The other scenario that can occur is that it can appear as a regular plane figure (its inclination is not apparent). Look at the purple face in the animation below

Now let us consider what happens when a sloped surface meets a Horizontal or Vertical surface. Where the two surfaces meet a line appears. This is because there is a change in direction. Look at what happens to the green and blue faces in the object below