If the angle of the two walls is less than 90 degrees just adjust the angle of the cut to less than 45 degrees so the two external edges meet or you will be left with a gap at the corner.
Tiling external corners.
In summary plan the installation of your tile trim alongside the installation of your tiles.
Place all the whole tiles on both walls either side of the corner.
Cut the final piece of tile on a wet saw to fit the wall so that its edge is flush with the corner.
Tiles can be installed in two different ways that utilise the corner.
When the adhesive has dried seal the angle between the 2 walls with a flexible waterproof.
Measure and cut a tile to fit the width of the gap to be filled.
Lay out the tiles along the first wall that comes up to the corner.
Http bit ly 1whjiir our how to tile around a window will give you all the skills you.
Use tile plastic corner trims for a neat look take accurate measurements before cutting the tiles.
Using a hacksaw or trim cutter cut the trim at a 45 angle at wall edges and bases and ensure that each portion.
Provides a rounded finish where tiles join at 90 angle either horizontally or vertically such as bath hobs or columns in a commercial application.
Either with tiles level to the top or tucked under to conceal the cut edge.
Butter the back with adhesive and press it into.
Measure the areas to be installed with tile trim and then them measure again to be 100 sure.
Here are a couple of pics hopefully they will make things clearer.