Triangle LMN is similar to Triangle MKN.
If we look at the smaller triangle created by the line from angle M, we can see that if we flip the smaller triangle so angles M and L would match up, the triangles are similar.
Triangle LMN is similar to Triangle LKM.
If we look at the entire triangle as a whole, we can see that is is a right triangle as well. As long as we remember to match up the angles, we can say that the triangles are similar.
Hope this helps!! :)