Is it possible to cut a square with a side of 1 m from a round sheet of iron with a diameter of 1.4 m.

Obviously, the diameter of a circle is equal to the diagonal of the largest square that can be cut from this circle. In our case, the diagonal is 1.4 meters. You can solve the problem in two ways:
a) Find the maximum possible side of the square from the maximum diagonal and compare it with the desired one.
b) From the required side of the square, find the diagonal of the required square and compare it with the maximum possible diagonal.
Let’s choose the second way: if the square has a side of 1 meter, then its diagonal is equal to:
√ (1 + 1) = √2 = 1.41421 …, which is larger than the maximum possible diagonal of the square, which means that a square with a side of 1 meter cannot be cut out of this circle.