![roof rafter calculator roof rafter calculator](http://2.bp.blogspot.com/-g_Zp6ithlkk/URbUDjBaJ5I/AAAAAAAASA8/NT3JT82jbbw/s1600/Shed_Roof_Law_Sines.jpg)
You only need to know two ratios, tangent and cosine. What is impressive about basic trigonometry is how ingenious and simple it is to use. This roof framing primer will show you how to employ these principles for building a garage roof or other wood-framed roof. While the theorem is limited to determining the length's of a triangle's sides, basic trigonometry can be used to find the degrees of angles as well. This equation describes the relationship between the sides and hypotenuse of a right triangle and is known as The Pythagorian Theory. A fellow named Pythagoras developed the equation, a² + b² = c² circa 550 B.C. Trigonometry is the branch of mathematics that rotates about the ratios between the sides of a right triangle which is any triangle with one (1) 90° angle where two legs meet. We hope to educate you in this Roof Framing Primer, so that you can tackle your own project of building a garage like a true craftsman. Once you master the basic trigonometry of the Right Triangle that we show you in this roof framing primer, your hand-held calculator will be as valuable a tool as your power-saw. Today, most carpenters when building a garage or other wood-framed project are using either a Rafter Table booklet they have acquired, a computer program found on a website, or a inexpensive hand-held calculator that fits right in their tool pouch.
![roof rafter calculator roof rafter calculator](http://1.bp.blogspot.com/-aNJVuS4r12U/URbLNGoMsAI/AAAAAAAAR_o/VLLvXArDulk/s640/Dormer_Shed_Roof_Law_Sines.jpg)
They may still be available, but I haven't seen one on a job-site in years. That square was the standard and authority on "angular lengths" (the hypotenuse) on every job site. In the old days of the early 1970s when I was interning as an architect, you could still purchase a "standard" 16" x 24" framing square that had all of the possible rafter length calculations printed on one side of it. For reference purposes, see our Garage Roof Framing page for a plan-view layout of the garage roof design we will be using in this Roof Framing Primer for building a garage roof.
![roof rafter calculator roof rafter calculator](https://www.carpentry-tips-and-tricks.com/images/spantakeridge.jpg)
By the time you finish you should have a clear picture of how to proceed on laying-out any garage roof framing plan before cutting a stick of valuable lumber material for building a garage. You will also learn how to use the modern-day 16" x 24" framing square for seat cuts and plumb cuts. In this Roof Framing Primer, you will learn how to calculate any rafter length using simple trigonometry and a hand-held scientific calculator the way many professional lead-man carpenters are doing it these days.