These are the notes for proving triangles are similar.
This a short video explaining the ways to prove triangles similar.
Source: https://www.khanacademy.org/math/geometry/similarity/triangle_similarlity/v/similarity-postulates
This video walks you through a few proofs involving similar triangles.
Source: http://www.youtube.com/watch?v=i4r2NHaAACc&safe=active
This is the key for the triangle similarity proof.
