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[ammornil]

$FD=DA=AE=2[cm], \quad EB=3[cm] \Rightarrow AB=5[cm]\\[12pt] S_{ABCD}=AB\cdot{}AD= 10[cm^{2}, \quad S_{DEC}=\dfrac{1}{2}\cdot{}S_{ABCD}= 5[cm^{2}]\\[6pt] S_{FDC}= \dfrac{1}{2}\cdot{}FD\cdot{}CD= \dfrac{1}{2}\cdot{}2\cdot{}5= 5[cm^{2}] \\[6pt] S_{FDEC}= S_{FDC} +S_{DEC}= 10[cm^{2}]$