Volume kerucut 8792 cm3 dan jari jari alas kerucut 20 cm jika phi=3,14.Hitunglah luas permukaan kerucut? BESERTA JALANNYA

Diketahui :
- Volume Kerucut = 8.792 cm³
- Jari - Jari Kerucut = 20 cm
- π = 3,14

Ditanya :
- Luas Permukaan Kerucut = .....?

Penyelesaian :
- Tinggi Kerucut :
V = ⅓ × π × r × r × t
8.792 = ⅓ × 3,14 × 20 × 20 × t
8.792 × 3 = 62,8 × 20t
26.376 = 1.256t
t = 26.376 ÷ 1.256
t = 21 cm

- Garis Pelukis :
s = √r² + t²
s = √20² + 21²
s = √400 + 441
s = √841
s = 29 cm

- Luas Permukaan Kerucut :
L = π × r × (r + s)
L = 3,14 × 20 × (20 + 29)
L = 62,8 × 49
L = 3.077,2 cm²

Maaf Kalau Salah

dik : V = 8792 cm³
r = 20 cm
π = 3,14

dit : L. per. kerucut ??

jawab :
→ V = 1/3 × π × r² × t
8792 = 1/3 × 22/7 × 20 × 20 × t
26376 = 22/7 × 400 × t
184632 = 22 × 400 × t
184632 = 8800 × t
184632/8800 = t
20,98 = t
dibulatkan
21 cm = t

→ s² = 21² + 20²
= 441 + 400
= √841
= 29 cm

→ L. per = π × r (s+t)
= 3,14 × 20 (29+21)
= 62,8 (50)
= 3140 cm²

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