geting ready to start laying polls for pole barn/shop that is 30'x60'. Trying to get all corners marked and squared. If we know the 2 end post locations (marked in red dots) theroetically we can measure over 60' along the front of shop and make an arc scribe then from our back known corner come across 67.082' (hypotenuse theory a2xb2=c2)and make and arc scribe and where they intersect is the corner right? Then repeat on other? Any other tips or ideas? Thanks.