Question

Suatu kerucut memiliki volume 1.884 dm3. Jika tingginya 8dm, tentukan : a.panjang jari jari alas ; b.panjang garis pelukis ; c.luas selimut ; d.luas permukaan

Answer 1

A )
V kerucut = 1884
1/3.phi.r².t = 1884
1/3.3,14.r².8 = 1884
25,12.r² = 1884.3
25,12.r² = 5652
r² = 5652 : 25,12
r² = 225
r = √225
r = 15 dm


b) s = akar dr r²+t²
= akar dr 15²+8²
= akar dr 225+64
= √289
= 17 dm


c) L selimut
= phi.r.s
= 3,14.15.17
= 800,7 dm²



d) L permukaan
= phi.r.(r+s)
= 3,14.15.(15+17)
= 3,14.15.32
= 1507,2 dm²