如图,BC长为3cm,AB长为4cm,AF长为12Cm.求CDEF的面积,用勾股定理,

AC^2 = AB^2 + AC^2 = 3*3 + 4*4 = 25
FC^2 = AC^2 + AF^2 = 25 + 12*12 = 169
所以 S(□CDEF)= FC^2 = 169