What is the sum of the angles of a decagon?

We are given a convex polygon (decagon) with n = 10 corners.
If you draw diagonals from each corner to opposite corners, then the diagonals will split it into (n-2) triangles.
The sum of the angles of the polygon coincides with the sum of the angles of the resulting triangles. The sum of the angles in a triangle is 180 degrees, so the sum of this polygon is (n-2) * 180 – the theorem on the sum of angles in a polygon.
Let’s apply for our polygon:
(10-2) * 180 = 1440 degrees.