1) Sebuah kerucut panjang jari-jari 9 cm dan tinggi 12 cm (phi=3,14). Tentukan: a. Panjang garis pelukis (s) b. Luas selimut kerucut c. Luas alas d. Luas kerucu

1). A. s²= r²+t²=9²+12²=81+114=√225= 15cm
B. Ls kerucut = πrs
=3, 14×9×15
= 423, 9 cm²
C. L alas = πr²
=3, 14×9×9
= 254, 34 cm²
D. Lp kerucut = πr(r+s)
= 3, 14×9×(9+15)
= 28, 26×24
= 678, 24cm²
E. V kerucut = ⅓πr²t
= ⅓×3, 14×9×9×12
= ⅓× 3, 052.08
= 1, 017.36cm³

2). A. V tabung = πr²t
1100 = 22/7×r²×14
r² = 1100×7:22×14
r. = 7700:308 =√25 = 5cm
B. Ls tabung =2πrt
= 2×3, 14×5×14
=6, 28×70
= 439, 6cm²
C. L alas = πr²
= 3, 14×5×5
= 78, 5cm²
D. Lp tabung = 2πr(r+t)
= 2×3, 14×5×(5+14)
=6, 28×5×19
= 311, 6 cm²

3) A. L bola = 4πr²
=4×3, 14×6×6
=12, 56×36
= 452, 16 cm²
B. V. Bola = 4/3πr³
= 4/3×3, 14×6×6×6
=4/3×678, 24
= 904, 32 cm³

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