Khan/khan-exercises — pull request #24021 by beneater (2012-06-15 21:24:05+00:00)
Title: Add exercise: Area of triangles 1

I give up.. the hints for obtuse triangles provide as satisfying an explanation as [10:50 in this video](http://www.khanacademy.org/math/geometry/basic-geometry/v/area-and-perimeter)

http://sandcastle.khanacademy.org/media/castles/beneater:triangle-area/exercises/area_of_triangles_1.html