Answer:
interior angle = 140°
Explanation:
the sum of the interior angle of a polygon is
sum = 180° (n - 2 ) ← n is the number of sides
here n = 9 , then
sum = 180° × (9 - 2) = 180° × 7 = 1260°
since the polygon is regular then interior angles are congruent, so
measure of each interior angle = 1260° ÷ 9 = 140°