742 Types 9, 11, 12, and 13: The Rice pentagons

- [Instructor] In this movie we'll look at…types nine, 11, 12, and 13…of the guaranteed to tessellate perfectly…irregular convex pentagons.…And to see what they look like,…I'll go ahead and click at this down pointing arrow head…in the bottom left corner of the screen…here inside the illustrator,…the one labeled Artboard Navigation…and I'll scroll down to this guy right here, Type 9.…So again, types nine and 10 are…out of order for reasons I do not know.…But I'll just go ahead and choose Type 9…which happens to be on Artbard 16…in order to see the first of four pentagons…discovered by Marjorie Rice in 1977.…

And this is a woman by the way,…who had nothing more than a high school education…and yet she was able to figure out more of these than anyone…but that first guy Karl Reinhardt back in 1918.…Alright so once again the angles up here in bold…and the sides appear in italics, and we've got these rules.…So, where the angles are concerned,…2A plus C is the same as D plus 2E…which adds up to 360 degrees.…Which as we'll see proves to be a little bit challenging.…