Showing posts with label trigenomtry. Show all posts
Showing posts with label trigenomtry. Show all posts

Thursday, September 9, 2010

Back to Grade 11 Math!


With the main floor framed, the second floor joists installed, and much of the subfloor above complete, I have to now calculate the length of the roof rafters. To keep things simple I cut all my joists at the desired roof pitch of 55 degrees, and will simply intall a 2" x 3" 'fascia stop' across the bottom end of all the joists, and then butt the rafter bottoms against this stop. This means no birdsmouth cuts, just a corresponding 55 degree cut at the rafter top to mate with the ridge.

Seeing that I couldnt recall whether 'soh cah toa' (or is it toh sah coa?) was correct, and whether angles had to be in degrees or radians, I chose the most efficient option. I just googled "trigenometry calculator" and got this incredibly simple online calculator. Input two of the values you know, and the other 3 are calculated for you!