Jawaban:
1. cari s dulu (garis pelukis) sisi miring segitiga
s² = 8² + 6²
= 64 + 36
= 100cm
s = √100cm = 10cm
luas permukaan = πr (r + s)
= 3,14 x 6cm x (6cm + 10cm)
= 18,84cm x 16cm
= 301,44cm²
2a. luas alas : πr² = 22/7 x 7² = 154cm²
b. luas selimut : πrs = 22/7 x 7 x 36 = 792cm²
c. luas permukaan = luas alas + luas permukaan
= 154cm² + 792cm²
= 946cm²
3a. garis pelukis s² = 15² + 8² = 225 + 64 = 289cm
s = √289cm = 17cm
b. luas alas = πr² = 3,14 x 8² = 200,96cm²
c. luas selimut : πrs = 3,14 x 8 x 17 = 427,04cm²
d. luas permukaan = 200,96cm² + 427,04cm²
= 628cm²
4a. tinggi kerucut = √s - r = √13² - 5² = 169 - 25
= √144cm = 12cm
b. luas permukaan = πr x (r + s)
= 3,14 x 5 x (5 + 13) = 15,7 x 18 = 282,6cm²
5a. jari² = d/2 = 14cm/2 = 7cm
b. luas permukaan = πr x (r + s)
704cm² = 22/7 x 7 (7 + s)
(7 + s) = 704cm²/22
= 32cm
s = 32cm - 7cm = 25cm
c. tinggi kerucut = √25² - 7² = 625cm - 49cm
= √ 576cm = 24cm
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