Equilateral triangle of A4 paper

Not origami, but still. I had a case not so long ago. I was listening to something, thinking about something, and bending a sheet of A4 paper. As a result, I went nuts because it was an equilateral triangle. I took a ruler, measured it - that's right.

I want to ask you, my dear: are there such methods already? I hardly the first.

PS I asked the Internet - they said they do not know.
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UPD: In sjavzi with minus and those who are searching for meaning:

Once again about the task:

There is a sheet of A4. Using only folds to make an equilateral triangle.

Question: who will come to the solution of the problem?

It is not easy, not difficult. This is not why.
I ask about the sequence of actions only.