Tolong dong Kak :) Pakai cara, no 19,20,21 ku kasih 40 poin

jawab

19
luas tabung = 471
r= 5
2π r ( r + t) = 471
10π (5+t) = 471
5+t = 15
t = 10

Vtabung  πr²t = π(25)(10)= 250 π = 785

20.
V diluar kerucut =  2/3 x Vtabung
= 2/3  x πr²t
= 2/3 . 22/7. 7². 12
= 1.232

21.
rb : rk = 1 : 2
rk = 2 rb

tk  = tb 
tk = 2rb

Vbola : V kerucut = 4/3 π rb³  : 1/3 π rk² tk 

Vb : Vk =  4 rb³ :  (2rb)²(2 rb)
Vb: Vk =  4 rb³ : 8 rb³  
Vb : Vk = 1 : 2

jawabannya :
19) → dik : L permukaan = 471 cm²
r = 5 cm
→ dit : V ??
jawab :
→ L = 2 πr (t+r)
471 = 2 × 22/7 × 5(t +5)
3297 = 44 × 5 (t+5)
3297 = 220(t+5)
3297/220 = t + 5
14,9 = t + 5
15 = t + 5
10 cm = t

• V = πr²t
= 3,14 × 5² × 10
= 31,4 × 25
= 785 cm³
jawabannya >> a.

20) → dik : r = 7 cm
t = 12 cm
→ dit : V luar kerucut ??
jawab :
• V luar = 2/3 × V tabung
= 2/3 × πr²t
= 2/3 × 22/7 × 7² × 12
= 2 × 22 × 7 × 4
= 1232 cm³
jawabannya >> a.

21) • r. bola : r. kerucut
= 1:2
• t. kerucut = 2r. kerucut

jawab :
→ V. bola : V. kerucut
= 4/3 π × r. bola ³ : 1/3 π × r. kerucut² × t. kerucut
= 4 r. bola ³ : (2r bola)²(2r. bola)
= 4 r. bola ³ : 8 r. bola ³
= 1 : 2
jawabannya >> c.

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