GDI, my math is rusty
Trying to figure out of much pipe I need to run an arc roof over the corral so I can turn it into a chicken run. I know the corral is ~40' wide, and I need it to be about 10' at its peak (maybe more, but if I can nail the original math, I can fudge it #s later), which is ~4 feet from the top of the posts I'm using to anchor the PVC pipe. My (really rough) guesstimate/instinct is I need ~60'-70' of pipe per "rib" (and they come in 10' lengths), but I'd feel a lot better if I could remember the formulas for arc length and circle geometry in general. 
On the upshot, the carpentry class of the local HS vocational wing has agreed to build me a chicken tractor based on the Cluckingham Palace. So,
On the upshot, the carpentry class of the local HS vocational wing has agreed to build me a chicken tractor based on the Cluckingham Palace. So,