13. (3 points) In the figure, the area of each circle is 1 square centimeter, then the area of the six-petal flower-shaped shaded part is $\qquad$ square centimeters.
【Answer】Solution: $1 \times 2=2$ (square centimeters);
Answer: The area of the shaded part of the six-petaled flower shape is 2 square centimeters. Therefore, the answer is: 2.