Dissection and Reassembly of Parallelogram of Given Base and Altitude
This Demonstration shows Wojtowicz's dissection of two parallelograms and with the same base and the same altitude.[more]
 A. McFarland, J. McFarland and J. T. Smith, eds., Alfred Tarski, Early Work in Poland: Geometry and Teaching, New York: Birkhäuser, 2014.[less]
The generalization of the caption is a theorem that two parallelograms of the same base and the same altitude can be decomposed into parts, where , is the altitude of the common part of the parallelograms (the red triangle) and .
Here denotes the least integer not less than the real number (the ceiling function) [1, pp. 127, 128].