Respuesta :

nktselepov

AB=CF=6cm, BC=A F=xcm

2BC+2x=20

2x=8

x=4, so BC=A F=4cm

AE=A F+EF

A F=4cm, EF=3cm

AE=4+3=7cm

[tex]S_{ABDE}=\frac{h(a+b)}{2} \\h=AB=6cm\\S_{ABDE}=\frac{6(9+7)}{2} =\frac{96}{2} =48cm^2[/tex]

Answer: S=48cm²

P.S. Hello from Russia :^)

Answer:

24

Step-by-step explanation:

Since the perimeter of ABCF=20

2(l+b)=20

l+b=10

Since AB is the given length substitute l=6

6+b=10

b=4

Now BD-BC=CD

9-4=5

Therefore CD=5

EF=3

CF=6(height)

Use the formula

I/2*(a +b)*h (here a & b are the parallel sides of the trapezium)

1/2*(5+3)*6

Cancel 6 and 2

8*3=24

Therefore the area of the trapezium is 24 square cm

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