Talk:My Little Pony Equestria Girls: Friendship Games/@comment-26837547-20150930082403/@comment-10390252-20150930083405

Unless 'F' was something unexpected like a third dimension extending out of the blackboard and thus impossible to show on the diagram; a little 'gotcha' just in case any of these smart-alec kids had sneaked into the hall to try to get a 'heads up' on that last stage.

Let's face it, both Twilight and Sunset are established as being genius-class intellects (and in Sunset's case is a lot older than the 16-year-old she presents as). A simple geometry problem wouldn't have really troubled either of them.