Basic Photography Lessons, The Golden Triangle Rule
This rule is useful if the scene is composed of many diagonal lines. The Golden Triangle Rule is a practical spin-off of the Golden Section Rule where the Diagonal Rule is also strongly applied at the same time.
First, a guide is made by drawing a line from one corner of the screen to the opposite corner. From this line draw perpindicular lines towards the other remaining corners, all in all forming four similarly shaped triangles, 2 large triangles, and 2 small triangles. Aligning the lines in your scene to these guide lines while positioning your subject on any of the intersections will make your photograph aesthetically pleasing.
Why is it called a Golden Triangle? The answer is simple, it effectively uses the same golden ratio used in a Golden Section. In fact, if you superimpose the guide for a Golden Section with this one, you will see that the intersections in the Golden Triangle fall on the same spots as the power points on a Golden Section.
Some photographers find it also effective to remove one of the small triangles forming three triangular sections, a large triangle, a medium triangle and a small triangle, and fitting the three most significant parts of a scene inside these triangles.