Does anyone know any informative links where I could learn more on the subject(Trapezoids, quadrilaterals, etc.)?
-Clueless
A few search engines for your enjoyment:
Should be something there for you. Is there anything in particular you want?
Here’s one for you to look at Trapezoid
Any high school geometry textbook should be able to help you. 
LL
In geometry the trapezoid has something to do with proving the area of something else. This is its main claim to worth as far as I know. In lore, the trapezoid shape is symbolic of an entry into the spirit world or the next world, etc. Coffins used to be in the trapezoid shape either for that reason, or else it is the other way around.
In other words the trapezoid is a door. Aesthetically it is an interesting shape in itself.