Jawaban:

1. 88 cm

2. 945 cm²

3. Tabung

4. No 1,3,4

5. 804 cm³

6. 1.920 cm³

7. 120 cm³

Penjelasan dengan langkah-langkah:

1. K = 2 × ½ πr²

= 2 × ½ × 22/7 × 28

= 2 × 11 × 4

= 22 × 4

= 88 cm

2. L. lingkaran = πr²

= 22/7 × 21²

= 22/7 × 441

= 22 × 63

= 1.386 cm²

L. persegi = s²

= 21²

= 441 cm²

= 1.386 – 441

= 945 cm²

3. Sisi alas dan bawahnya lingkaran disebut tabung.

4. Karena ketiganya bukan jaring - jaring kubus.

5. V. kubus = s³

= 6³

= 216 cm³

V. Balok = p × l × t

= 7 × 12 × 9

= 588 cm³

= 216 + 588

= 804 cm³

6. V. balok = p × l × t

= 15 × 8 × 12

= 1.440 cm³

V. limas = ⅓ × la × t

= ⅓ × 120 × 12

= 40 × 12

= 480 cm³

= 1.440 + 480

= 1.920 cm³

7. V = ⅓ × la × t

= ⅓ × 36 × 10

= 12 × 10

= 120 cm³

Semoga bermanfaat

Maaf jika salah

Makasih...