Diagonal
line segment joining two nonconsecutive vertices of a polygon or polyhedron
Diagonal is a kind of straight line. A diagonal line does not go straight up and down, or across left and right. It is a line that connects two corners of a shape.
In mathematics, "diagonal" has different meanings. For example, in geometry a diagonal is any line that goes between the corners of a polygon. So a square has two diagonals, and a five-sided shape has five diagonals. In general the count of diagonal can be identified by a formula [n(n-3)]/2 where n is the total number of sides of shapes.
