# Ratio

Navigation: Menus > Measure Menu > # Ratio |

Selection prerequisites: Two segments or three collinear points

Collinear points are points that lie on the same straight line.

This Measure menu command measures the ratio of two lengths or distances.

• | If two segments are selected, this command measures the ratio of the length of the first selected segment to the length of the second.

• | If three collinear points A, B, and C are selected in order, this command measures the ratio of the distance AC to the distance AB.

If points B and C are on the same side of A, the ratio is positive; if B and C are on opposite sides of A, the ratio is negative.

Another way to think of the ratio defined by three collinear points is to think of a number line with its origin at point A and its unit point at B. The position of point C on this number line determines the value of the measurement.

C is between A and B, so the ratio is between 0 and 1. | C is beyond B, so the ratio is greater than 1. | C is beyond A, so the ratio is less than 0.

If point C is constructed on straight object AB, the ratio measurement is the same as the value of point C on its path. In this case it’s easier to select only point C and choose Measure | Value of Point.