How many diagonals are there in a polygon with n=50 sides?

In a polygon, the sides are the lines that join
consecutive points. All other lines between points that form the polygon are called
diagonals.

For example, the simplest polygon which is a
triangle does not have any diagonals as all the lines drawn between points that form the
polygon are sides of the triangle. A rectangle has 4 sides and 2
diagonals.

The number of sides that a polygon has is equal
to the number of points that make up the polygon. As examples, triangles have 3 sides
and are formed by 3 points, rectangles have 4 sides and are formed by 4 points,
etc.

A polygon with 50 sides is formed by 50 points. The
number of lines joining consecutive points is 50 and these are the sides of the polygon.
All lines between non-consecutive points are called
diagonals.

From each point of the polygon we can draw 47
diagonals. But the diagonal between two points is the same irrespective of which point
is considered the starting point and which is considered the ending point. This gives
the number of diagonals as 50*47/2 = 1175

The
number of diagonals in a polygon with 50 sides is
1175.