Perimeter

Selection prerequisites: One or more polygon, arc sector, or arc segment interiors.

Measures the perimeter of each selected polygon or arc interior, using the distance units chosen on the Units panel of the Preferences dialog box. The perimeter of an arc sector is the sum of the arc length and the lengths of the two radii bounding the arc sector. The perimeter of an arc segment is the sum of the arc length and the length of the chord bounding the arc segment.