Answer :

To find the sum of the measures of the interior angles of a decagon, we first need to understand some basic properties of polygons.

A decagon is a polygon with 10 sides. The formula to find the sum of the interior angles of a polygon with [tex]\( n \)[/tex] sides is given by:

[tex]\[ (n - 2) \times 180^\circ \][/tex]

where [tex]\( n \)[/tex] is the number of sides of the polygon.

For a decagon ([tex]\( n = 10 \)[/tex]):

1. Substitute [tex]\( n = 10 \)[/tex] into the formula:
[tex]\[ (10 - 2) \times 180^\circ \][/tex]

2. Simplify the expression inside the parentheses:
[tex]\[ 8 \times 180^\circ \][/tex]

3. Multiply the numbers:
[tex]\[ 1440^\circ \][/tex]

Therefore, the sum of the measures of the interior angles of a decagon is [tex]\( 1440^\circ \)[/tex].

The correct answer is:
C. 1440°