PreAlgebra
posted by mysterychicken .
Can someone help me with this one
Quadrilaterals are a special type of polygon because _______________.
A. they always have exactly four sides
B. the sum of their interior angles always measures 180°
C. they always have opposite sides that are parallel
D. they are always concave
Thanks
MC

Look at what a simple Google search found.
http://www.google.com/search?source=ig&hl=en&rlz=1G1GGLQ_ENUS328&q=Quadrilaterals&aq=f&oq= 
Thanks
MC