Card #348: Adding similar triangles 3 for visually identifying similar triangles

Maureen described the format: https://trello-attachments.s3.amazonaws.com/4d87e664967a0775082939ab/4f1a178858aefe9310156ea4/GkFdOA2eLEugc24G0mxbmUbAvdkx/Similarity_of_Triangles_1.jpg

The ask is to create triangles to train the user to visually identify similar triangles. To do this, I generated a not-so-random list of triangles to differentiate between, and scaled them as done in Maureen's original.

I altered the question slightly to only accept a single answer from the multiple choice. From chatting with Ben, it seems that multiple answers is not an option for the multiple choice questions (this could be an addition to the trello board for prioritization/triage). 

Nit: in the hints, the triangle.labels.angles overlap, due to the scaling of the triangles. Any tips on how to fix this?

-seema

This is my first pull request, guidance is appreciated.