Answer:
width of a river = 45m
Step-by-step explanation:
ration and proportion
let x = width of a river
x 20.9 m
------ = --------
56 m 26 m
x = (20.9 * 56) / 26
x = 45 m
therefore the width of a river is 45 m
Continuing from the setup in the question linked above (and using the same symbols/variables), we have




The next part of the question asks to maximize this result - our target function which we'll call

- subject to

.
We can see that

is quadratic in

, so let's complete the square.

Since

are non-negative, it stands to reason that the total product will be maximized if

vanishes because

is a parabola with its vertex (a maximum) at (5, 25). Setting

, it's clear that the maximum of

will then be attained when

are largest, so the largest flux will be attained at

, which gives a flux of 10,800.
I believe it would be 12, I believe this because its states that it is TWICE as long therefore is made from the same metal so 6x2=12
38 cm sum of all sides is equal to the perimeter