Question 1172018
Original radius, 4
Changed radius, 8


{{{(2pi*8)/(2pi*4)}}}

{{{2}}}

Circumference is doubled.



{{{(pi*8^2)/(pi*4^2)}}}

{{{8^2/(4^2)}}}

{{{(2^6)/(2^4)}}}

{{{4}}}

Area became four times as large.


You should be able to solve parts (C) and  (D).