tolong bantu caranya

L daerah yang diarsir = L APOB
2× 3/4 × L lingjaran + L APOB = 228,4
2 × 3/4 × 22/7 × r^ + r^ = 228,4
3/2 × 22/7 r^ + r^ = 228,4
(33/7 r^) + ( 7/7r^ ) = 228,4
( 40/ 7 r^) = 228,4
r^ = 228,4 × 7/ 40
r^ = 39,97 = 40 cm ^
# tanda ^ = kuadrat