We already now what the bottom two sides lengths are but we need to find the length of the top 2 sides.
To find the side lengths we can use the area of the right triangle on the top with the area of 15 in. to do that we need to find the lengths of the two dotted red lines making the right triangle using process of elimination the lengths of the left side is 3 the bottom length is 10. the we use the Pythagorean theorem to find the length of the perimeter. 10^2+3^2=109 109/2= 54.5. the length of the top two sides are 54.5. To now find the perimeter we add the length of one of the top 54.5 and one of the bottom 45 to get 99.5 then multiply it by 2 99.5*2= 199 the perimeter of the window is 199 in.
