An involute of a square is the path traced by the endpoint of a rope unwound from around its perimeter. To draw it, start with constructing a 25mm side square and calculate its perimeter (100mm). Mark points along this length using arcs equal to each side's length, extending lines at these marks. Trace smooth curves connecting these points or use compass adjustments for precision. To add tangent and normal lines on any point along the curve, extend one line as normal through that point towards one corner; then draw another perpendicular to it as tangent.