How this calculator works
Dropping perpendiculars from the shorter base removes two congruent right triangles. Each has horizontal leg half the difference of the bases. The diagonal instead spans the average base horizontally. These relationships allow area, perimeter, diagonal or an angle to reconstruct the same shape. The calculator requires unequal bases; a rectangle belongs to the rectangle tool.
Formula
x=(L-S)/2; m=(L+S)/2; leg²=h²+x²; diagonal²=h²+m²; K=mh; P=L+S+2leg; acute angle=atan(h/x).
Worked example
Bases 10 m and 4 m leave an offset of 3 m on each end. Height 4 m gives 5 m legs, area 28 m², perimeter 24 m and equal diagonals √65 m.
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Frequently asked questions
Is the leg the same as the height?
The leg is slanted and longer than the perpendicular height when the bases differ.
Can I start with area?
Yes. With both bases fixed, height is area divided by their average, which then determines the legs and angles.
Why reject a short diagonal?
Its horizontal span is already the average base length. A diagonal no longer than that cannot leave a positive height.