Volume kerucut =770 cm3. Jika tinggi=15 cm dan phi =22/7. Hitung lah jari-jari alas kerucut?

diket :
v = 770 cm³
t = 15cm
π = 22/7
dit r

v = 1/3×πr²t
770 = 1/3×22/7×r²×15
770 ÷ 1/3 = 22/7×r²×15
770 × 3 = 22/7×r²×15
2310 = 22/7×r²×15
2310 ÷ 22/7 = 15r²
2310 × 7/22 = 15r²
105 × 7 = 15r²
735 = 15r²
735 ÷ 15 = r²
49 = r²
[tex] \sqrt{49} [/tex] = r
7cm = r