The sum of the internal angles of the quadrilateral is 360, while the sum of the internal angles of the sectors of the three shaded parts in the image is 360-90 = 270 (three sectors with the same radius can be combined into a large sector with a sector angle of 270).

Circumference =2π× radius

So the radius = the circumference of the circle ÷2π(π is 3. 14).

R =18.84 ÷ 6.28 = 3cm

So the area of three sectors = (sum of internal angles of sectors ÷ 360) × area of circle = (270 ÷ 360 )× 3? ×3. 14 = 2 1. 195 cm2

The answer is 2 1. 195 square centimeters. This question tests students' ability to sum the internal angles of quadrilateral, the formula of pi, the formula of circle area and image processing.

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