The ratio between each triangle inside the triangle is 1.618 and that is the golden ratio. (Phi) Golden triangles are used in different shapes such as decagons or different pentagons, which are used in architecture.
The golden rectangle is the most desired ratio and most pleasing rectangle to look at. In architecture its used a ton and used in most building plans so that people will look at it and it will be pleasing to look at. Its display Fibonacci sequence because the ratio of the out side rectangle in all of Fibonacci ratio.