61. A rectangle, the length of which does not exceed four times the width, is to be cut into three pieces from which a square can be formed.
61. Cutting a rectangle into three parts and forming a square from them is shown in Figure 82. If $a$ and $b$ are the lengths of the sides of the rectangle, then the method used is applicable only if $\sqrt{a b} \geqslant 0.5 a$, i.e., $4 b \geqslant a$.