luas daerah yang diarsir adalah

△ABC = △ABD - △ACD
= (9 × 8 ÷ 2) - (9 × 2 ÷ 2)
= 36 - 9
= 27

△CDE = △AED - △ACD
= (9 × 12 ÷ 2) - (9 × 2 ÷ 2)
= 54 - 9
= 45

L. Arsir = △ABD + △CDE
= 27 + 45
= 72 cm^2