SOLUTION: Will you please help me with this word problem? I don't understand how to use pi and write formulas from these problems. A semicircular window of radius 10 inches is to be lamin

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Question 310945: Will you please help me with this word problem? I don't understand how to use pi and write formulas from these problems. A semicircular window of radius 10 inches is to be laminated with a sunblock coating that costs .85 per square inch to apply. What is the total cost of coating the window, to the nearest cent? (use pi=3.14. hint: area of circle is A=pi r^2)
Found 2 solutions by Fombitz, mollukutti:
Answer by Fombitz(32388) (Show Source):
You can put this solution on YOUR website!
Remember is just a number. There's nothing magical about it.
You're charged by the area for the coating so calculate the area of the window.
If it was a whole circle, the area would be . Since it's 1/2 a window (semi-circle) the area would be half that
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Total Cost=Cost/Area * Area
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TC==$133.45.

Answer by mollukutti(30) (Show Source):
You can put this solution on YOUR website!
Cost per sq inch is .85
We know Area of a circle = Pi x r^2 where r is the radius
Pi= 3.14
Radius= 10
Area of the circle= Pi x r^2
= 3.14 x 10^2
= 3.14 x 100
= 314
The given window is semicircular in shape, hence its area will be half the area of the above circle
= 314 / 2
= 157 sq inches
Hence cost of coating the window will be 157 x .85 = 133.45