Essential Figures — Rectangles: continued  Perimeter = 2l + 2w  Area  =  l × w  Trapezoids:     Characteristic Notes    The top line (of length d) and the bottom line, a.k.a. the base, (of length b) are parallel lines; the altitude is of height h, while the two sides are of length a and c... Perimeter = a + b + c + d  Area  =  ½ (b + d ) h Special Cases...  d = 0    ____________   b = d ≠ h    ____________   b = d = h     ____________