Quadrilateral
A quadrilateral is a four sided polygon.
Example 1
![Picture](/uploads/1/5/9/5/15954846/1369192965.jpg)
This scene in Harry Potter and the Goblet of Fire takes place the night before the first task in the Triwizard Tournament when Harry is sneaking down to the common room to talk with Sirius in the fireplace. The frame of one of the paintings in the common room is shaped like a quadrilateral.
"The common room was deserted, and, judging by the fact that it smelled quite normal, Hermione had not needed to set off any Dungbombs to ensure that he and Sirius got privacy." -Harry Potter and the Goblet of Fire, Page 330
Example 2
![Picture](/uploads/1/5/9/5/15954846/1369883833.jpg)
This scene in Harry Potter and the Sorcerer's Stone takes place when Harry is checking the mail. The envelope of the letter in Harry's hand is shaped like a quadrilateral.
"Harry picked it up and stared at it, his heart twanging like a giant elastic band. No one, ever, in his whole life, had written to him. Who would? He had no friends, no other relatives — he didn't belong to the library, so he'd never even got rude notes asking for books back.Yet here it was, a letter, adressed so plainly there could be no mistake:
Mr. H. Potter
The Cupboard under the Stairs
4 Privet Drive
Little Whinging
Surrey"
-Harry Potter and the Sorcerer's Stone, Page 34