Respuesta :

Behind that one that 2 that 3 00000 break it down chop it up 2 a half 2 a whole

Answer:

15. 12, 16. 18

Step-by-step explanation:

a = pi*r^2

15) 36pi = pi*r^2 --> 36 = r^2 --> 6 = r --> 12 = d

16) 81pi = pi*r^2 --> 81 = r^2 --> 9 = r --> 18 = d