Answer:
a) 12870°
b) 17
c) 50
Explanation:
Part a
The Polygon Interior Angle-Sum Theorem states that the sum of the measures of the interior angles of a polygon with n sides is (n - 2) · 180°.
The number of sides of a 73-gon is n = 73. Therefore, the sum of its interior angles is:

Therefore, the sum of the interior angles of a 73-gon is 12870°.

Part b
The Polygon Interior Angle-Sum Theorem states that the sum of the measures of the interior angles of a polygon with n sides is (n - 2) · 180°.
Given the sum of the interior angles of a regular polygon is 2700°, then:

Therefore, the number of sides of the regular polygon is 17.

Part c
According the the Polygon Exterior Angles Theorem, the sum of the measures of the exterior angles of a polygon is 360°.
Therefore, to find the number of sides of a regular polygon given its exterior angle is 7.2°, divide 360° by the exterior angle.

Therefore, the number of sides of the regular polygon is 50.