Jay: follow the bouncing ball ROFLOL the back or farthest pc IS STRAIGHT PC :}:} You then cope the sides INTO that pc.
Now this is the most difficult part, super secret, complicated part.
make your cope cuts as good as you can, leave the pcs long, butt them into the back pc and SMACK THE END with a hammer to drive that coped end tighter, then mark the mitered ends right along the corner they are on, NO RULERS NEEDED.DO NOT NAIL THEM YET, the opposing sides of the mitered corners repeat the process, cope em whack em, scribe em, then put em together and all should br nice and tight then nail the beaches :yes::laughing: I will send the invoice for "Trim School" :wink::whistling2: