tolong dijawab ya plissssss

trapesium
(a+b) × t : 2
= (58+42) × 21 : 2
= (100) × 21 : 2
= 1.050

setengah lingkaran
22/7 × r × r : 2
= 22/7 × 21 × 21 ÷ 2
= 693

1050 - 693 = 357 cm