When sketching, you can explicitly enter a value for the sketch line by typing a number after you begin the sketch line.
Typically, listening dimensions specify linear dimensions such as length of a line, the length of a chord (when drawing the second point of a 3-point arc), or the length of a radius (when drawing an arc, circle, or polygon). If there is no linear dimension, you can enter an angular dimension, if applicable. Listening dimensions are not available for some elements, such as splines and rectangles.
Use listening dimensions to specify line length
The sketch line is drawn the specified length.