Find the area of the unwatered region to the nearest square meter.

eddy2017 said:
I think i will use the formula for half a circle. It is what I have here. 3 half a circles or semicircles.
So,
72m-(1/2 pi r squared)
I got the length which is 18m all across.
I need to find the radius to solve for half the circle.
If I split 18 into three parts then I find that each of the half circles has a diameter of 6 .
The radius is half the diameter, so, each radius measures 3 meters, so I have the radius .
I'll plug it into the formula for a semicircle, taking into account that are 3 semicircles.

72- 3(1/2 pi 3²)
72-3(1/2 pi 9)
Let's simplify.
72-(3*0.5*3.14*9)
72-42.39
=29.6
This is the are covered by the sprinkler system.
So, now I will subtract this area from the total area of the plot to find the the area of the dry zone.
Okay?.
Click to expand...
72-42.39=29.6 is not correct. Try subtracting again.
I do have one concern. You clearly wrote 72m-(1/2 pi r squared) and then wrote 72- 3(1/2 pi 3²). Where did the 3 suddenly come from or should the 3 have been in the other equation.
 
Jomo said:
72-42.39=29.6 is not correct. Try subtracting again.
I do have one concern. You clearly wrote 72m-(1/2 pi r squared) and then wrote 72- 3(1/2 pi 3²). Where did the 3 suddenly come from or should the 3 have been in the other equation.
Click to expand...
=29.61.
For me, it should be,
3(1/2 pi r²)
Because there are three semicircles,so, I need to multiply the formula for finding the area of a half circle by 3.
 
Last edited:
Jomo said:
72-42.39=29.6 is not correct. Try subtracting again.
I do have one concern. You clearly wrote 72m-(1/2 pi r squared) and then wrote 72- 3(1/2 pi 3²). Where did the 3 suddenly come from or should the 3 have been in the other equation.
Click to expand...
Yes, it should have been.
 
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