A trapezoid has four sides and four vertices. A vertex is a corner of a polygon. According to Reference.com, a trapezoid is a quadrilateral plane figure that has two parallel sides and two non-parallel sides.
All four-sided figures have four corners, or vertices. The perimeter of a trapezoid is determined the same way as that of a square or rectangle: the length of all four sides are added together. The area, however, is not determined the same way. For squares and rectangles, the area is determined by the formula area equals length times width. The formula for the area of a trapezoid is area equals one-half the sum of the two bases times the height.