The answer is,

Also equivalent to about, 0.185188.
Completing the square follows the principle of taking

and converting it into

where d is the 'correctional number' as I like to call it - i.e. the number that converts the expanded bracket into the +c, since the expanded bracket will give us

.
In this case, 2/2=1 so we have the first part:

.
Expanding this gives us

. We need c to be 9, so we can just add 8.
Putting this together:

Now we can solve it more easily.
Rearranging:
Step-by-step explanation:
formula to find volume of a cylinder => V= πr²h
(22/7×(3.5)²×12)cm³
462cm³.
now the total volume of plastic used is = 462×0.2 = 92.4cm³.
hope this helps you.