I don't see a problem but I will rewrite the structure.

Make two rectangles attached together.

Call the first rectangle ABHG (AG top, BH bottom).

Call the second rectangle GHCD (HC top, GD bottom).

Draw a horizontal line from line AB to line GH and name the points E on line AB and F on line GH.

example:

A----G-------------D
|.........|..................|
|.........|..................|
E----F..................|
|.........|..................|
|.........|..................|
|.........|..................|
|.........|..................|
B----H-------------C

Rectangles AEFG, EBHF and GHCD are similar.

The length of AE is 4cm.
The length of EB is 9cm.

What is the area of rectangle GHCD ?
What are the lengths of HC and EF ?

Given AE=4, EB=9,

If AE≠EB, the only way that AEFG and EBHF are similar is that AE<EF<EB, which means really that
AEFG is similar to FEBH to ensure the vertices correspond.

If that's the case,
Let EF=x, then
AE/x = x/EB, or
x² = AE*EB = 36
EF = x = 6 (negative root rejected)

Now for the rectangle GHCD, there are two ways to be similar to rectangle AEFG, i.e.
HC=(2/3)GH, or
HC=(3/2)GH

I will let you complete the problem.

I looked at it another way.

I used rectangle FEBH; area = 9 x EF.
I used rectangle AEFG; area = 4 x EF.

Ratio of area FEBH to AEFG = 2.25

The square root of area is ratio of the perimeters = 1.5

Perimeter of AEFG = 2 x 9 + 2 x EF
Perimeter of FEBH = 2 x 4 + 2 x EF.

Since FEBH is 1.5 larger than AEFG then
1.5 x (8 + 2EF) = 18 + 2EF,
12 + 3EF = 18 + 2EF,
1EF = 6.

Now I know ratio of AE / EF = 2/3.

It works out the same FE / HF = 2/3.

Therefore GH / HC = 2/3,
13 x 3 / 2 = HC = 19.5.

Therefore the area of GHCD =
13 x 19.5 = 253.5

Is this correct ?

That is correct, but HC=19.5 is only one of the two possible solutions.

If HC=13*(2/3)=26/3, the rectangles are still similar (but turned 90°).
So the other solution is
Area = 13*(26/3) = 112.67

Thank you for all your help.

O_O

To find the area of rectangle GHCD, we need to find its dimensions. We can do this by using the given information about the dimensions of rectangle AEFG and EBHF.

Rectangle AEFG and EBHF are similar, which means their corresponding sides are proportional. The length of AE is 4cm and the length of EB is 9cm. Hence, the ratio of the lengths of corresponding sides in AEFG and EBHF is 4:9.

Using this ratio, we can determine the length of side GH in rectangle GHCD. Since AEFG and GHCD are attached rectangles, the length of AE in AEFG is also equal to the length of GH in GHCD. Thus, the length of GH is also 4cm.

Now, we know the length of side GH in GHCD is 4cm. To find the length of HC, we can subtract the length of EB (9cm) from the length of side GH (4cm). Therefore, the length of HC is 4cm - 9cm = -5cm.

However, a length cannot be negative, so we made an error in our calculations. We need to reassess the given information and ensure that the lengths are correct.

As for the length of EF, it is not specified in the diagram or provided information. Thus, we cannot determine its length without additional information.

In conclusion, we are unable to find the area of rectangle GHCD or determine the lengths of HC and EF with the given information as there seems to be an error in the dimensions provided.