Isosceles Trapezoid - Trapezoid with the two non parallel sides equal. The perimeter of a polygon is the distance around it. If you remember this basic fact then the various perimeter formulas will be easy to remember. The area is a measure of how much space there is inside a geometric figure. It is measure in a different kind of unit from the units of length that are used for perimeter.
Area is measure in square units.
If the lengths are measured in centimeters, then the area is measured in square centimeters. Square centimeters are little square 1 cm by 1 cm, and the area is how many of those little squares it takes to cover the figure. The idea is to imagine you have a bunch of those squares and some scissors and glue and you wanted to fill up the area with them and you can cut them any way you want to, but you have to fill up the area completely and with no overlapping. The number of squares that it would take to do this is the area. One thing to be careful with in areas is that there are two common ways of writing square units.