Cut a piece of craft paper or butcher's paper so it's the same size as your laminate flooring plank. You can use any type of paper to do this, but craft paper and butcher's paper work extremely well. If you use smaller pieces of paper, you can tape them together then cut them to size.
Place the paper in the location where you will install the laminate flooring plank and need to cut laminate corners.
Tape the paper to the floor so it doesn't slip while you work. Don't use so much tape that the paper tears when you pick the paper up, but use another to secure it in place.
Fold the paper along the edges of the wall. Fold the paper up on itself and tape the loose edge down. Do this around the corner and down the length of the laminate flooring plank. It may be necessary to tear the paper as you make the fold, and that's fine. Just make sure you don't tear the portion that lays where you will eventually install your laminate flooring corners.
Pull the paper off the floor gently, so you don't tear it. This acts as your template for cutting laminate flooring corners.
Place the paper template on the back of your laminate flooring plank. Make sure the tongue side and the groove side of the plank face the same way as your template, so your cut fits the right way. Trace the template on the back of your laminate flooring plank.
Cut your laminate flooring plank with a circular saw according to the drawings you made on the back of your plank.
Install your laminate flooring plank in the appropriate location and you'll have a smooth fit in your corner. Snap the two planks together to secure the laminate floor corners in place.