First, The equilateral triangle is divided into three isosceles triangles of two sides L = 1 and and angles 30, 30 and 120.
Second. The triangle isosceles is divided into two rrectangular triangles.
The hight of the triangle isosceles H = Radius of circle x sen 30, then H = 0,5
The base of the triangle isosceles B = 2 x Radius of the circle x cos 30 = 1,732
Then , tthe area of one triangle is 1,732 x 0,5 / 2
The total area of the internal triangle is 1,732 x 0,5 / 2 x 3 = 1,3
The area of the blue shaded zone is 1 x Pi - 1,3