trapezform

Trapezform, or trapeziform, is a quadrilateral that features a pair of opposite sides that are parallel. The parallel sides are called the bases, while the other two sides are the legs. If exactly one pair of opposite sides is parallel, the figure is a trapezform; if both pairs are parallel, the shape is a parallelogram and is not usually classified as a trapezform in standard treatment. Terminology for these shapes can vary by region, but the defining idea remains a quadrilateral with a parallel pair.

The height of a trapezform is the perpendicular distance between its bases. The area is given by A = h × (a + b) / 2, where a and b are the lengths of the two bases and h is the height. The perimeter is P = a + b + c + d, where c and d are the lengths of the legs. In any trapezform, the interior angles adjacent to the same base are supplementary, and the sum of all interior angles is 360 degrees.

Special cases include the isosceles trapezoid, where the legs are equal in length and the diagonals are equal; base angles on each base are also equal. A right trapezoid has one leg perpendicular to the bases, yielding two right angles at one base.

Trapezform shapes occur in various practical contexts, such as architectural cross-sections, ramps, and roof profiles. They also appear in three-dimensional geometry as trapezoidal prisms formed by extruding a trapezform along a perpendicular axis.