en.wikipedia.org/wiki/Internal_and_external_angles

In geometry, an angle of a polygon is formed by two sides of the polygon that
share an endpoint ... The sum of all the internal angles of a simple polygon is 180
(n–2)° where n is ... The ...

www.regentsprep.org/regents/math/geometry/gg3/lpoly1.htm

Sum of Interior Angles of a Polygon. = 180(n - 2) (where n = number of sides) ...
Notice that a pentagon has 5 sides, and that 3 triangles were formed by ...

www.qc.edu.hk/math/Junior Secondary/interior angle.htm

Sum of Interior angles of an n-sided polygon. There are many ... The point P
chosen may not be on the vertex, side or inside the polygon. It can even be a
point ...

www.mathsisfun.com/geometry/interior-angles-polygons.html

The Interior Angles of a Triangle add up to 180° ... If it is a Regular Polygon (all
sides are equal, all angles are equal) ... Sum of Interior Angles = (n-2) × 180°.

www.dummies.com/education/math/geometry/interior-and-exterior-angles-of-a-polygon/

Exterior angle: An exterior angle of a polygon is an angle outside the ... The sum
of the measures of the interior angles of a polygon with n sides is (n – 2)180.

www.algebra.com/algebra/homework/word/geometry/Geometry_Word_Problems.faq.question.450813.html

The formula for the sum of the interior angles of a polygon with n sides is (n - 2)
180° We set that equal ... So each of the other 11 interior angles measures 148°.

www.mathopenref.com/polygoninteriorangles.html

... and repeat. Note the behavior of the interior angles and their sum. ... So for a
polygon with N sides, there are N vertices and N interior angles. For a regular ...

www.maplesoft.com/support/help/Maple/view.aspx?path=MathApps/SumofInteriorAnglesOfAPolygon

For example, a triangle has three interior angles, with a sum of 180. As the
number of sides, n , of a polygon increases, the sum of its interior angles,...

www.math-only-math.com/sum-of-the-interior-angles-of-a-polygon.html

Therefore, the sum of interior angles of a polygon having n sides is (2n – 4) right
... Find the sum of the measure of interior angle of a polygon having 19 sides.

www.math.com/school/subject3/lessons/S3U2L1DP.html

We can use a formula to find the sum of the interior angles of any polygon. In this
formula, the letter n stands for the number of sides, or angles, that the polygon
has. ... by 180, the sum of the measures of all the interior angles in a triangle.