Obtuse Triangle
An obtuse triangle is a triangle with at least one angle that measures more than 90°.
Example 1
This scene in the movie Harry Potter and the Deathly Hallows, Part 1 takes place in the Gordric's Hollow graveyard, where Harry and Hermione are searching for Harry's parents' grave. At this moment Hermione is showing Harry a grave with a familiar mark on it.
"The grave was extremely old, weathered so that Harry could hardly make out the name. Hermione showed him the symbol beneath it. 'Harry, that's the mark in the book!' He peered at the place she indicated: The stone was so worn that it was hard to make out what was engraved there, though there did seem to be a triangular mark beneath the nearly illegible name." -Harry Potter and the Deathly Hallows, Page 327
Example 2
This scene in the movie Harry Potter and the Deathly Hallows, Part 1 takes place at the Ministry of Magic. At this moment, Harry and his friends are just getting off a lift in the Atrium. The design above the lifts contains an obtuse triangle.
"They managed to cram themselves into two lifts. Harry's Patronus stood sentinel before the golden grilles as they shut and the lifts began to rise." - Harry Potter and the Deathly Hallows, Page 265