90 Degree Angle:

Ever wonder how to figure out what "square" is?  Here's a technique which is useful indoors or out for determining a true 90 degree angle on a large scale. Use it when laying floor tile, framing walls, building decks, putting down wood floors, hanging ceiling tile, and just about any other construction project. . Indoors, use marks on the floor; outdoors use strings and stakes in the ground to mark the points you measure out.

The procedure is simple: Make a right triangle that is 3 feet on one side, 4 feet on the other and 5 feet on the diagonal measurement. You now have a perfect 90 degree angle on the 3 foot and 4 foot sides to build from.

45 Degree Angle:

By following these directions you can determine a true 45 degree angle, which is useful in flooring and decking applications.

Begin by using the following math formula:

A squared (A multiplied by itself) plus B squared equals C squared. 

We can use this to determine a true 45 degree angle. Following this math formula and by using two legs of the triangle that are the same length we are creating an equilateral triangle. The drawing shows how this is done. You can choose any measurement for A and B as long as they are the same. For example, if you choose 3 ft for A and B, then C will be 4 ‘ 3" long (A squared…3x3=9, B squared…3x3=9) (then 9+9=18)( What number times itself equals 18?…4.2426 feet = 4 ¼ feet = 4 feet 3 inches) In our example A equals 3 feet, B equals 3 feet, so C equals 4 feet 3 inches.  Plot them out on your floor or outside and you have two lines with a right angle you can follow.  and who ever said geometry wasn't fun?