Please help...

Let's start with the very basics and see where we end...

Simple 1x4 frame.

Internal vertical ID of frame measures PRECISELY 71 5/8"s. At both the left and right meeting points, the middle, and a spot on both the L and R that are equidistant from the middle.

Horizontally: ID of frame measures PRECISELY 127 1/4 " at both the top and bottom and middle.

What does this tell me? It tells me I have rectangle with opposing sides that are just about dead nuts parallel, therefore, I should yield (4) 90 degree corners when both the mirrored vertical and horizontal identical boards are laid out.

A quick 3/4/5 of the corners yields a dead-nuts 90 degree yield on all 4 corners.

So what's the problem?

I come up with a 147 diagonal and a 145 diagonal on the opposed.

I have been sitting in my garage contemplating this for 45 minutes and I simply cannot come up with an answer to this problem that jives with any geometry/trig I'm aware of.

Equal lengths with parallel sides should yield diagonals that are identical. Simple as that.

After confirming both sides (x2) are identical in length and parallel, I do not know where else to go.

I'd love for someone to point out the err of my way.

Thanks a ton.

James

Let's start with the very basics and see where we end...

Simple 1x4 frame.

Internal vertical ID of frame measures PRECISELY 71 5/8"s. At both the left and right meeting points, the middle, and a spot on both the L and R that are equidistant from the middle.

Horizontally: ID of frame measures PRECISELY 127 1/4 " at both the top and bottom and middle.

What does this tell me? It tells me I have rectangle with opposing sides that are just about dead nuts parallel, therefore, I should yield (4) 90 degree corners when both the mirrored vertical and horizontal identical boards are laid out.

A quick 3/4/5 of the corners yields a dead-nuts 90 degree yield on all 4 corners.

So what's the problem?

I come up with a 147 diagonal and a 145 diagonal on the opposed.

I have been sitting in my garage contemplating this for 45 minutes and I simply cannot come up with an answer to this problem that jives with any geometry/trig I'm aware of.

Equal lengths with parallel sides should yield diagonals that are identical. Simple as that.

After confirming both sides (x2) are identical in length and parallel, I do not know where else to go.

I'd love for someone to point out the err of my way.

Thanks a ton.

James