Question 953663
The top line of the roof separates the roof space into a cross section with a base 9 feet, an angle of {{{125/2=62&1/2}}} degrees opposite the 9 foot base, and this is a right triangle.  The other angle along the top edge of the shed, the square part, is {{{180-90-62&1/2=27.5}}} degrees.


You want to know the hypotenuse which is one of the dimensions of half of the roof.


{{{cos(27.5)=h/9}}}, h for hypotenuse;
{{{h=9*cos(27.5)}}}


Now, ONE surface of the roof is {{{9*9cos(27.5)}}}; and there are two of these, so the entire roof surface area is  {{{highlight(2*9*9cos(27.5))}}}



(I know, a picture would help.)