bantuin, tentang kesebangunan dll (kalo soalnya gaada gambar maklum, berarti aku lupa masuin gambarnya.)

no 21)

PS² = QS x SR

QS = PS²/SR

QS = 6²/9

QS = 4

no 22)

panjang karton/panjang foto = lebar karton/lebar foto

20/(20-2-2) = 30/(30-2-x)

20/16 = 30/(28-x)

5/4 = 30/(28-x)

140-5x = 120

-5x = -20

x = 4

no 23)

ST/PQ = RS/PR

ST/24 = 20/30

ST/24 = 2/3

3 ST = 48

ST = 16

no 24)

volume awal = 20

1/3 π r² t= 20

1/3. 1/4 π d² t = 20

1/12 π d² t = 20

π d² t = 240

diameter diperbesar 2 kali, tinggi diperbesar 3 kali, berarti

1/3 .1/4. π (2d)².t =

1/12.π.4d².t =

1/3 π d² t =

1/3(240) =

80

no 25)

2π r t =

2.22/7.7.12 =

528