Odpowiedź:
|AB|=|CD|=10cm
|BC|=|AD|=6cm
|BF|=1/3x6cm=2cm
DG|=4/5|CD|
|DG|=4/5x10cm=8cm
|AH|=2/3|AD|
|AH|=2/3x6cm=4cm
PEFGH=PABCB-(PΔEBF+PΔCFG+PΔDGH+PΔAEH)
PEFGH=6cmx10cm-(1/2x5cmx2cm+1/2x4cmx2cm+1/2x8cmx2cm+1/2x4cmx5cm)
PEFGH=60cm²-(5cm²+4cm²+8cm²+10cm²)
PEFGH=60cm²-27cm²
PEFGH=33cm²