It is important to understand the use of the square. The base, rise and hypotenuse of the square used in the different methods herein given solve the practical use of the square. Every inch to 8" rise, with 12" base, gives 8 different cuts on either of the three lines, and 8 different pitches of roof. It also gives eight cuts for braces, brackets, bridging and truss framing. In roof framing, the hypotenuse is the pitch of the roof and the length of the rafter in one base foot. (See fig. 29.) Any cut in framing may be obtained with 12" base and the required number of inches rise. There may be a hundred or more different rises from the base and every one is a square root, or geometrical problem, but can be worked out with the square in a practical way without the knowledge of either square root or geometry.