There are 4 rectangles.
Width = x
Length = x + 8
On the top of the shape, there is 1 width and 1 length. On the right side of the shape, there of 1 width, 1 length, and 1 length minus width. On the bottom of the shape, there is 1 width and 1 length. On the left side of the shape, there is 1 width, 1 length, and 1 length minus width.
90 = (x + x + 8) + (x + x + 8 + x + 8 - x) + (x + x + 8) + (x + x + 8 + x + 8 - x)
90 = 2x + 8 + 2x + 16 + 2x + 8 + 2x + 16
90 = 8x + 48
42 = 8x
x = 5.25 cm
Area = length x width
Length = 5.25 + 8 = 13.25 cm
Width = 5.25 cm
There are 4 rectangles. The length and width is known of each.
Area of 1 rectangle = 13.25 x 5.25 = 69.5625 cm^2
Area of 4 rectangles = 69.5625 x 4 = 278.25 cm^2
The area of the 8-sided shape is 278.25 cm^2.
Hope this helps!! :)
