So the area of triangle ABF =(3/ 10) the area of square ABCD.

=(3/ 10)x30=9 cm2,

The area of triangle DFC =(2/ 10) the area of square ABCD.

=(2/ 10)x30=6 cm2,

Because AE=( 1/2)EF,

So the area of triangle BEF =(2/3) the area of triangle ABF,

Because the area of triangle ABF =( 1/2) the area of square ABCD.

=( 1/2)x30

= 15 cm2，

So the area of the triangle BEF =(2/3)x 15.

= 10 cm2,

So the area of quadrilateral EFBC = the face of triangle BEF+the area of triangle DFC.

= 10+6

= 16 cm2。

2。 The intersection d is DG//BC, and the intersection AE is G point.

Because f is the midpoint of the CD,

So triangle GDF is equal to triangle ECF(A, s, a).

So DG=EC,

Because BE=2EC,

So BE=2DG, BE/DG=2,

Because DG//BC,

So AB/AD=BE/DG=2, AB=2AD, and d is the midpoint of AB.

So the area of triangle ACD =( 1/2) the area of triangle ABC.

=( 1/2)x 1

=1/2cm2,

Because f is that midpoint of the CD,

So the area of triangle ADF =( 1/2) the area of triangle ACD.

=( 1/2)x( 1/2)

=1/4cm2,

Because BE=2EC,

So the area of triangle ACE =( 1/3) the area of triangle ABC.

=( 1/3)x 1

=1/3cm2,

So the shadow area = the area of triangle ABC-the area of triangle ACE-the area of triangle ADF.

= 1-( 1/3)-( 1/4)

=5/ 12 cm2。

3。 Link DE

Because AE=EF=FB,

So the area of triangle ADF =( 1/3) the area of rectangle ABCD.

=( 1/3)x(6x2)

=4,

Triangle area ADE =(2/3) Triangle area ADF

=(2/3)x4

=8/3,

Area of triangular EDF =( 1/3) area of triangular ADF.

=4/3,

Because AB//DC, AE=EF=FB.

So FO/OD=EF/DC= 1/3.

So the area of triangle DOE =( 1/4) the area of triangle EDF.

=( 1/4)x((4/3)

= 1/3,

So the area of shaded part = the area of triangle ade+the area of triangle DOE.

=8/3+ 1/3

=3。