Perhatikan bangun A dan B sebangun

Jawaban:

8/14 =x /21

14 x = 8.21

14x = 168

x = 168 : 14

x = 12

luas trapesium B = 1/2 (a+b) . t

= 1/2 (12 + 21).12

= 1/2 (33). 12

= 33. 6

= 198 cm²