In the paper "division of square paper" among other is told the way of exact division of the side of the square into three parts. Having spent only five minutes, Mokhov Aleksey found one more decision of this task with accuracy more than one percent from the side of the initial square. And up to this moment he never was engaged in origami. Inspired by this example you can try to find the decisions by this or similar tasks.

However, we shall return to consideration of the offered way. At first we shall tell about this way, and then - mathematical estimation of accuracy. Let's mark the centre of the square and fold to it one of the corners. On the created crease we have to mark the quoter of it. And, at last, we shall fold another corner of square to this point.

Now we shall check up, as far as exact this decision is.

From the theorem by Pithagor it follows, that for a finding value of x it is enough to solve the equation (5-x)²+1²=x². This equation it is possible to transform to the more simpe 26-10x=0. Thus, x=2,6. That makes 2,6/8 from the party of an initial square. Hence error makes approximately 0,008 parties of an initial square.