To construct a 90-degree angle, what must be done after drawing arcs on either side of the line?

To construct a 90-degree angle, the next step after drawing arcs on either side of the line is to join up the points where the arcs cross. This is important because when you draw arcs from two points on one side of the line, they will intersect at two points. By connecting these intersection points with a straight line through the original point of the angle, you effectively create the angle that is perpendicular to the original line, thereby achieving a 90-degree angle.

This method leverages the geometric principle that an angle can be accurately constructed by using circle arcs to find the correct intersection points, ensuring precision in the drawing of right angles. Each intersection point allows for a clear representation of the desired angle, highlighting the significance of this step in the overall construction process.