This shape's namesake numbers are also known as polite numbers, and when this figure's diagonals break it down into four triangles, the result is exactly one pair of triangles with equal areas; dividing that equal area by the areas of the other triangles gives reciprocals. Approximations using this 
This shape's namesake numbers are also known as polite numbers, and when this figure's diagonals break it down into four triangles, the result is exactly one pair of triangles with equal areas; dividing that equal area by the areas of the other triangles gives reciprocals. Approximations using this shape generally give a worse result than Simpson's Rule but a better result than Riemann sums when approximating integrals. Its area is usually given by the formula half the sum of the bases times the height, and it has a median which is parallel to its bases and whose length is the average of them. Name this quadrilateral with one pair of parallel sides.
This shape's namesake numbers are also known as polite numbers, and when this figure's diagonals break it down into four triangles, the result is exactly one pair of triangles with equal areas; dividing that equal area by the areas of the other triangles gives reciprocals.
{trapezoid} [or {trapezium}]