Interesting Primary School Mathematics competition question-2

I just saw a very interesting post on matrix67, the original http://www.matrix67.com/blog/archives/4485.

I have always written a classic Primary School geometric question. If you have not read this question, you must check it out. An Oracle Primary School instructor Zeng

I was told that when I led the students to participate in this competition, the leaders and teachers did not think of the "primary school student solution" of this problem, so that they began

Check whether this question is beyond the outline. After seeing the answer, the teachers are very impressed-there is indeed a wonderful solution without any geometric knowledge.

Today, I am going to take a primary Olympics class on a temporary basis. I saw this question: ABCD is a square, the side length is 4, and defg is a rectangle,

Where DG = 5, calculate the length of the De. In other words: the question itself is not difficult, and everyone knows the answer at a Glance. The key to the question is,

This is a primary school competition question, which means that this question must have an exceptionally clever and foolish solution. This solution does not need to be simplified,

You don't need column equations. In fact, you almost don't need anything. You only need to use the basic and most obvious square rectangle.

Can you think of this solution? (The answer is as follows)

I called a few Junior High School Mathematics Teachers and studied it for a long time. The results were similar to those of my head,

So I had to seek help from the teachers in the primary school group. I really got the truth, and I was full of likes. Connect AG,

Note that the area of the triangle ADG is both half of the area of the square ABCD and half of the area of the rectangle defg.

The square area is equal to the area of the rectangle. Since the square area is 16, one side of the rectangle is 5, and the other side is 3.2.
Did you think of it?