Thanks, Melody...
Here's another way without using Calculus
Positioning the circles as Melody did :
![](/img/upload/261e9f89b1468cd10b0ef7f5/capture243.jpg)
The intersection of two circles at the left side of the figure occurs at A = (sqrt(3) , 3)
Similarly, the intersection of the two circles at the bottom occurs at ( 3, sqrt (3) )
So the distance between these two points is AD = sqrt [ 24 - 12 sqrt (3) ] cm
Therefore...using symmetry....we can construct a square AFGD of this side with an area of [ 24 - 12sqrt(3)] cm^2 (1)
Looking at the segment AE... the slope of this segment = 3/sqrt (3) = sqrt (3)
Looking at the slope of DE....the slope of this segment is sqrt (3) / 3 = 1 / sqrt (3)
So arctan (sqrt (3) ) - arctan (1/sqrt(3) ) = 60° - 30° = angle AED = 30°
So the area of sector AED is (1/2)(12)(pi/6) = pi cm^2
And the area of triangle AED = (1/2)(12)sin(30) = 3 cm^2
So....the area between the sector and the triangle is [pi - 3] cm^2
And using symmetry....4 of these areas = [4pi -12] cm^2 (2)
So....the shaded area is (1) - (2) =
[ 24 - 12sqrt (3)] - [ 4pi - 12 ] cm^2 = [ 36 - 12sqrt (3) - 4pi] cm^2 (exact) ≈ 2.65 cm^2 (rounded)
![cool cool](/img/emoticons/smiley-cool.gif)