Question 918319
The window looks like this:
{{{drawing(200,300,-5,5,-10,5,
rectangle(-3.75,0,3.75,-8.8),
red(arc(0,0,7.5,7.5,180,360)),
red(arc(0,0,7.55,7.55,180,360)),
red(arc(0,0,7.45,7.45,180,360)),
red(line(-3.75,-8.8,-3.75,0)),
red(line(3.75,0,3.75,-8.8)),
red(line(-3.75,-8.8,3.75,-8.8)),
locate(-0.9,-0.05,7.5ft)
)}}}
The {{{red(perimeter)}}} is 3 sides of the rectangle (1 width and 2 lengths) plus the half circumference at the top.
If the width is 7.5 ft, that is also the diameter of the semicircle,
so the circumference would be {{{7.5pi}}} and half a circumference is {{{7.5pi/2=3.75pi}}} .
We have the bottom (the width) and the top (the half circumference), adding up to
{{{7.5+3.75pi}}} feet.
The rest of the perimeter is the 2 vertical sides, (2 lengths of the rectangle), so
{{{2*length+7.5+3.75pi=39.6}}}
In approximate numbers,
{{{2*length+7.5+11.781=39.6}}}
{{{2*length+19.281=39.6}}}
{{{2*length=39.6-19.281}}}
{{{2*length=17.619}}}
{{{length=17.619/2}}}
{{{length=8.8095}}} feet.
 
The area is the area of the rectangle part plus half of a circle.
{{{8.8095*7.5+(1/2)*pi*3.75^2=66.071+22.089(rounded)=88.16}}} square feet (rounded to 2 decimal places).