Question 310945
Remember {{{pi}}} 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 {{{A=pi*r^2}}}. Since it's 1/2 a window (semi-circle) the area would be half that {{{A=(1/2)pi*r^2}}}
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Total Cost=Cost/Area * Area
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TC={{{0.85*(1/2)(3.14)(10)^2}}}=$133.45.