Answer:
To find the sum of the measures of the interior angles of any polygon, we can use the formula:
Sum of interior angles = (n-2) x 180 degrees
where n is the number of sides (or vertices) of the polygon.
So, for an 18-sided polygon, we can substitute n = 18 into the formula:
Sum of interior angles = (18 - 2) x 180 degrees
Sum of interior angles = 16 x 180 degrees
Sum of interior angles = 2,880 degrees
Therefore, the sum of the measures of the interior angles of an 18-sided figure is 2,880 degrees.