Question

I need help with this question

Answer 1

Answer:
_______________________________________________
1) 72
`\pi` cm² / min. ;
_______________________________________________
2) 192
`\pi` cm² / min.
_______________________________________________
Step-by-step explanation:
____________________________________________

Area of a circle: A =
`\pi` r² ;

Rate of change of Area is: da/dt = 2
`\pi` r (dr/dt) ;

Given: dr/dt = 3 cm / min.
______________________________________________________
Problem 1)
____________________________________________________________
dA/dt = 2
`\pi` *(12 cm)*(3 cm/ min) = 72
`\pi` cm² / min. ;
____________________________________________________________
Problem 2)
____________________________________________________________
dA/dt = 2
`\pi` *(32 cm)*(3 cm/ min) = 192
`\pi` cm² / min.
_____________________________________________________________