dik volume kerucut 314 cm jari jarinya 5cm (π3,14) dit luas kerucut

314=1/3.3,14.5.5.t
314=1/3.78,5.t
t=314:78,5.3
t=4.3
t=12

luas kerucut=3,14.5.5 + 3,14.5.13
78,5+221= 299,5