trapezoidal is part of:
    50%  tapered

trapezoidal contains:

Full expansion for trapezoidal:
    95%  1x6x3 Trapezoidal Basin End-Cap
    90%  3x4 Notched Trapezoidal Plate
    90%  3x4 Tri-Slope Brick w/ 1x2 Top
    90%  4x4 Angular Cockpit Bottom
    90%  4x4 Dual-Tapered Dual-Notched Brick
    90%  4x4 Dual-Tapered Sloped Brick,1x2 Top
    90%  4x4 Dual-Tapered Stingray Sloped Brick
    90%  4x4 Notched Trapezoidal Nose Brick
    90%  6x7 Trapezoidal Boat Plate
    80%  3x6x3 Trapezoidal Basin Dumping-End
    80%  6x7 Notched Trapezoidal Boat Brick
    80%  6x7 Notched Trapezoidal Boat Deck
    80%  6x8 Thick Trapezoidal Lattice Plate
    70%  8x8 Notched Trapezoidal Plate