When a circle is too large to be drawn with a pair of dividers, what should you use?

Using a trammel is the correct approach when a circle is too large to be created with a standard pair of dividers. Trammels are tools specifically designed for drawing large arcs or circles; they consist of a straight beam fitted with sliding markers or arms that can be adjusted to the desired radius. This makes it possible to create large-scale circles by pivoting the beam around a central point while simultaneously keeping the distance consistent with the radius.

In contrast, a protractor is utilized primarily for measuring angles rather than drawing large circles. A compass is designed for drawing smaller circles and is not suited for larger radii due to its limited reach. A ruler, while useful for measuring straight lines, does not provide a means for creating arcs or curves. Therefore, the trammel stands out as the most effective tool for this specific task.