18. (6 points) Given that the side length of each small square in the figure is 4 cm, find the area of the shaded part?



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【Answer】Solution:
The area of the rectangle $(4 \times 4) \times (2 \times 4) = 128$ (square cm)
The area of the blank triangle at the top left $4 \times (2 \times 4) \div 2 = 16$ (square cm)
The area of the blank triangle at the top right $4 \times 4 \div 2 = 8$ (square cm)
The area of the blank triangle at the bottom right $4 \times (4 \times 4) \div 2 = 32$ (square cm)
The area of the shaded part $128 - 16 - 8 - 32 = 72$ (square cm)
Answer: The area of the shaded part is 72 square cm.