Originally Posted by Jan in VA

Looks like it's a 45 degree tilt. You could also do a 30 degree tilt; both are on most 6" x 24" rulers and some 6" x 12" rulers.

When you have cut the borders, you will have bias edges on them.
Here's a little trick to help stabilize those biases. The graphic is not drawn exactly for your situation, but the idea still applies.

Jan in VA