Final answer:
The interior angles of any 4-sided figure, or quadrilateral, sum up to 360 degrees, derived from the general formula for polygon interior angles which is (number of sides - 2) x 180 degrees.
Step-by-step explanation:
The interior angles of any 4-sided figure, known as a quadrilateral, add up to 360 degrees. This rule is a result of extending the concept of triangles having interior angles that sum up to 180 degrees. The formula to calculate the sum of interior angles of a polygon is (n - 2) × 180 degrees, where 'n' is the number of sides in the polygon. For a quadrilateral, 'n' equals 4, and hence the sum of its angles is (4 - 2) × 180 degrees = 2 × 180 degrees = 360 degrees.
The interior angles of any 4-sided figure, also known as a quadrilateral, always add up to 360 degrees. This can be proved using the fact that a quadrilateral can be divided into two triangles. Since the sum of the interior angles of a triangle is 180 degrees, the sum of the interior angles of two triangles is 360 degrees.