9.This is because it goes through the whole circle passing through the centre point. at the full width
The rest are pretty easy. I'm sure you can manage. Good luck!
The dimension that would give the maximum area is 20.8569
<h3>How to solve for the maximum area</h3>
Let the shorter side be = x
Perimeter of the semi-circle is πx
Twice the Length of the longer side
![[70-(\pi )x -x]](https://tex.z-dn.net/?f=%5B70-%28%5Cpi%20%29x%20-x%5D)
Length = ![[70-(1+\pi )x]/2](https://tex.z-dn.net/?f=%5B70-%281%2B%5Cpi%20%29x%5D%2F2)
Total area =
area of rectangle + area of the semi-circle.
Total area =
![x[[70-(1+\pi )x]/2] + [(\pi )(x/2)^2]/2](https://tex.z-dn.net/?f=x%5B%5B70-%281%2B%5Cpi%20%29x%5D%2F2%5D%20%2B%20%5B%28%5Cpi%20%29%28x%2F2%29%5E2%5D%2F2)
When we square it we would have
![70x +[(\pi /4)-(1+\pi)]x^2](https://tex.z-dn.net/?f=70x%20%2B%5B%28%5Cpi%20%2F4%29-%281%2B%5Cpi%29%5Dx%5E2)
This gives
![70x - [3.3562]x^2](https://tex.z-dn.net/?f=70x%20-%20%5B3.3562%5Dx%5E2)
From here we divide by 2

The maximum side would be at

This gives us 20.8569
Read more on areas and dimensions here:
brainly.com/question/19819849
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A
This is because 4x18 = 72
Hope this helps
3 pipes take 12 hours
⇒ In 1 hour, the 3 pipes can fill 1/12 of the pool
2 of the pipes take 18 hours
⇒ in 1 hour, the 2 pipes can fill 1/18 of the pool
In 1 hour, the third pipe alone can fill :

Time needed :

----------------------------------------------------------------------------------------
Answer: It will take 36 hours for the third pipe to fill the pool.----------------------------------------------------------------------------------------
Answer:
is in quadrant II
Step-by-step explanation:
Given
and 
Required
Where is 
and
imply that
is in quadrant II
Because that is only quadrant where
and
exist.