diagonala paralelipipedului =21 cm
diagonala bazei=√(21²-20²)=√(441-400)=√41 cm
latura₁ a bazei=5 cm
latura₂ a bazei=√(√41)²-5²=√(41-25)=√16=4 cm
Perimetrul bazei=(4+5)x2=18 cm
Aria bazei=4x5=20 cm²
Aria laterala=Pxh=18x20=360 cm²
Atotala=360+20x2=400 cm²
V=20x20=400 cm³