Volume kerucut 3.696cm³, Tinggi 18cm Berapa panjang jari - jari alas kerucut?

v = 1/3 phi x r x r x t
3.696 = 1/3 x phi x r x r x 18
3.696 x 3/18 = phi x r x r
3.696 x 1/6 : phi = r x r
616/phi = r x r
616 x 7/22 = r x r
28 x 7 = r x r
7 x 2 x 2 x 7 = r x r
14 x 14 = r x r
r = 14