mitreing edges?

[BARCUD]

Hi all, the top of my bathroom cabinet I have just made obviously isn't square on top! I've tried to put pieces around the top edges for decoration.
The mitered edges dpn't match !!! surprise surprise. I used a 45% angle on a measuring square. Is there a tip or method for cutting angled edges that will meet on corners that aren't square?

 

[Jackrae]

Measure the angle, divide by 2 and the result is the mitre angle required. For example, if the angle is 94 degrees, the required mitre angle is 47 degrees.

Alternatively, you could lay/tape one section of facing on the unit (horizontal facing), then lay/tape the other section (vertical facing) over this. Where the two pieces cross each other, make index marks on the inner and outer edge of the vertical facing, these indicate the cut line. Cut the vertical facing and then use this to establish the cut line on the horizontal facing

One further technique is to lay a sheet of paper over the face of the cabinet corner and trim this to exactly the shape of the corner. Let us say the corner is 94 degrees. Now fold the paper diagonally edge to edge and the resultant angle (47 degrees) is the exact angle you need to cut the mitres to. Simply lay the folded paper over the facings and scribe off against the folded edge. The beauty of this system is that no measurement is required and the established angles are exact mitres.

 

[BARCUD]

Cheers Jack, I knew there must be a way but couldn't suss it out. I'll get into the shed tomorrow and let you know which method I use and if I get it right.
many thanks.