Jika jari jari alas kerucut =5cm dan tinggi kerucut =12cm hitunglah a/ luas permukaan bandul b/volume bandul

a). luas kerucur = phi×r(r+s)
cari s terlebih dahulu.
s kuadrat = r kuadrat + t kuadrat
s kuadrat = 5×5 + 12×12
s kuadrat = 25 + 144
s kuadrat = 169
s = 13cm
luas = phi×r(r+s)
= 3.14×5(5+13)
=15.7×18
=282.6cm kuadrat
b). volume = 1/3×phi×r kuadrat×t
= 1/3×3.14×5×5×12
=314 cm kubik