no 25,28,30,31 tolong dia jawab pake cara

25.
luas 2/6 lingkaran
= 2/6 x TT x r x r
= 2/6 x 22/7 x 21 x 21
= 462 cm^2 (A)

28. luas permukaan balok
= 2 x p x l + 2 x p x t + 2 x l x t
= 2 x 32 x 25 + 2 x 32 x 10 + 2 x 25 x 10
= 1600 + 640 + 500
= 2740 cm^2 (B)

30. volume bangun tersebut
= volume prisma segitiga + volume kubus
= luas alas x tinggi + rusuk x rusuk x rusuk
= 1/2 x 25 x 20 x 20 + 20 x 20 x 20
= 5000 + 8000
= 13000 cm^3 (C)

31. volume air
= volume balok
= p x l x t
= 10 x 8 x 5
= 400 dm^3 = 400 liter (A)