No 19 dan 20 gimana??? Pakai caranya ya..

20.L. lingkaran=phi×r2
=22/7×28^2
=2464 cm
L. juring= =90°/360°=luas juring/2464
=1/4=aob/2464
4aob=2464
Aob=2464÷4=616 CM
L.Segitiga=1/2×a×t
=1/2×28×28
=1/2×784=92 CM
L. Yg diarsir=LUAS JURING-LUAS SEGITIGA
=616-92=524 CM

19) L = L segitiga 1 + L segitiga 2
= (1/2×12×16) + (1/2×15×20)
= 96 + 150 = 246 m^2 (C)
20) L = L 1/4 lingkaran - L segitiga samasisi siku-siku
L = (1/4 × phi × r^2) - (1/2 × r^2)
= (1/4 × 22/7 × 28^2) - (1/2 × 28^2)
= 616 -392
= 224 cm^2 (C)