tolong dijawab no 20-23 pake cara ya....

20.=3/4×22/7×35×35
=2.887,5cm^2

21. ACD=1/2AOB
40°=1/2AOB
AOB=80°

22.sudut juring tak diarsir=360°-45°=315°
Luas juring=315/360×22/7×28×28
=2.156cm^2

23.panjang busur=120/360×22/7×28
=29,33cm

20. π x r²
      22/7 x 35² x 3/4 = 22 x 5
                       = 82,5 cm²
21. ∠AOB = 2 x ∠ACB
                 = 2 x 40° = 80°
22. luas juring OAB = ∠AOB/360° x πr²
                                = 45°/360° x 22/7 x 28²
                                = 0,125 x 2464 = 308 cm²
23. α/360° x 2πr
     = 120°/360° x 2 x 22/7 x 14
     = 29,3 cm²