How to square of sheets of Plywood

[GlennSpray68]

Hi all,

Please bare with me and forgive me if this is a stupid question .
I have several large off cuts of plywood and would like to build a drawer unit with .

The problem I have is none of the corners on the sheets are 90 degrees and I cannot figure out how to cut them down to enable me to start off with square boards . An exaggerated version is pictured below.

I thought that if I use a framing square from one edge that would give me a reference point to square from but that didn't work out properly .

I have a speed square , framing square and a circular saw , with a diy straight edge guide , that cuts square if that helps.

Any help or advice would be much appreciated

Many thanks in advance

Glenn

 

[big-all]

you need to start with a strait edge so make sure you have a strait edge before marking
once you have a strait edge go central with your roofing square draw a line flip the square and draw a line beside the other one to check the square

 

[GlennSpray68]

Thanks Big All will check that out first.