740 Types 6–8: The Kershner pentagons

- [Instructor] In this movie, we'll take a look…at what are known as Types 6-8…of the famous tessellating pentagons.…And, so, if you're working in the same files I am,…drop down to the bottom left corner of the screen.…Click on this down pointing arrowhead,…labeled Artboard Navigation.…And, then, just go ahead and scroll down the menu…until you see this guy, artboard 12 Type 6.…And click on it, in order to navigate to that artboard.…And, you'll see, whereas the Type 5 pentagon…was first discovered by Karl Reinhardt, back in 1918,…the Type 6 was discovered by a guy named Richard Kershner,…a full 50 years later.…

And it ends up looking like this.…So, recall that the bold letters…indicate the angles between the sides.…And the italic letters indicate…the lengths of the sides themselves.…And so the rules this time around…are that angles B and D add up to 180 degrees.…And, then, if you take angle B and multiply it times two,…you get angle E, over here on the left hand side.…Where the signs are concerned,…B and C are equal to each other, as are sides A, D, and E.…