Since each square will have an area of 4 cm^2 because they are congruent, then let’s find the side length of them.
Square root of 4 is two
Each side is 2 cm. Since the unshaded triangle has 3 on the base and height, then it is same to assume that the triangle has a base of 6 cm (2 * 3) and a height of 6 cm.
The formula of the area of a triangle is: 1/2 ( base times height)
Let’s plug in some values
1/2(6 * 6)
Multiply
1/2 (36)
Divide
18
Since the triangles are also congruent, then the shaded side has the same area.
All you have to do is add up the side lengths we already know then subtract by the perimeter. 60.3 is the side lengths all together that we know 82-60.3=21.7 Hope this helped!!