Technical Drawing - Interpenetration - Solid Penetration

In this section we will look at how we draw the penetration of a plane surface by a solid square based prism.  Below you can see the problem that you should lay out one your page if you wish to work along or attempt this question first.  The labeling has been left out of the question. You should try and do this yourself before looking at the first step of the solution.
You should be able to see from the orthograhic projection that we have a solid square based prism parallel to the HP penetrating a plane surface which is at an angel to the VP.  Below are the stages in the completion of this question.
You may not have labeled the points of importance the same but do not worry about this so long as you have the labeling format correct.

In the plan view it is easy to see where the square based prisms edges 1, 2, 3 and 4 intersect with the plane surface.  Project these points into the Elevation as shown above.
We now show the lines which are hidden, (again you do not have to do this unless you have to). Part of the plane surfaces edge ac is behind the square based prism and the square based prism goes behind the plane surface before it reaches the edge bd.
Your completed drawing should look like this.
Your completed drawing without construction or hidden lines would look like the above drawing.