To visualize the figure, as illustrated, will aid in fixing this Theorem in mind. Do the same with others. Another example of emphasizing the important lines as in the Theorem:
Two rectangles are to each other as the products of their bases by their altitudes.
In the illustration below the bases and altitudes are emphasized to remind you of the fact that they are the factors to be dealt with. Notice that in the first pages of the Geometry all simple figures are illustrated as explained or defined. Learn to visualize the problem with your book closed, work until you can see it clearly, and you will understand it better.
AIDS IN STUDYING CHEMISTRY
Experiments in Chemistry are its most interesting phase. Let its problems take form in your visual mind and you will add to the enjoyment and also the ease of your understanding.
A teacher of this subject, after appreciating the value and ease of visualization, worked out picture combinations of atoms which helped him greatly. He could see the two atoms of Hydrogen floating through the air and combining with the atom of Oxygen and could see the result of the combination.