Why are there three piles of things in the fence? Where are these three piles hit?

On the same plane, there must be at least three line segments to form a graph.

Fences are usually rectangular, square and trapezoidal.

In fact, the piles of the fence are equivalent to the line segments on both sides of the above three shapes, and they are contracted to the underground extension lines for fixation.

For the fence to be erected, a pile is enough for the protruding part.

But to stand firm and not be blown around the central axis of a pile, a fence needs at least two piles.

Then why is there usually three piles in a fence? A fence is a simple fence, which is used in the garden outside the field. In the process of construction, it is usually made into semi-finished products, that is, rectangles with a length of 2 to 3 meters (the height is determined according to needs). In addition to fixing the two sides with piles and adding a fixed pile in the middle, the wall can be stronger after it is erected.

This is a common practice in production practice. There are two, three and more than four piles, but usually three piles are the most commonly used. Fences with appropriate length are also convenient for handling and dismantling.

Physiologically, two piles are enough.