Jawab:
(1.) Tinggi 9 cm
(2.) jari-jari 7 cm

Penjelasan dengan langkah-langkah:

(1.) Diketahui kerucut
Volume (v) = 115.5 cm³
Jari (r) = 3.5 cm
π ≈ ²²/₇
Dicari: tinggi (t)

v = ⅓×π×r²×t
3×v = π×r²×t
t = (3×v)÷(π×r²)
maka
t = (3×115.5)÷(²²/₇×3.5×3.5)
t = (346.5)÷(22×0.5×3.5)
t = (346.5)÷(11×3.5)
t = 346.5÷38.5
t = 9 cm
Tinggi 9 cm

--------------------------------

(2.) Diketahui:
Volume (v) = 770 cm³
tinggi (t) = 15 cm
π ≈ ²²/₇
Dicari: jari-jari (r)

v = ⅓×π×r²×t
3×v = π×r²×t
r = √[(3×v)÷(π×t)]
maka
r = √[(3×770)÷(²²/₇×15)]
r = √[2310÷(³³⁰/₇)]
r = √[2310×(⁷/₃₃₀)]
r = √[7×7]
r = √49
r = 7 cm
jari-jari 7 cm

<(7o7)>