tolong jawab 14 sampai 15 kalau bisa pakai cara yah

14)La = 1/2 x a x t
= 1/2 x 12 x 10 = 6 x 10 = 60
V = La x t
480 = 60 x t
480/60 = t
t = 8

15)r = 20 x 1/2 = 10
V = 1/3πr²t
= 1/3 x 3,14 x 10² x 18
= 157/150 x 100 x 18
= 314/3 x 18
= 5652/3
= 1884