$A$ polygon has $44$ diagonals. The number of its sides is

How many chords can be drawn through $21$ points on a circle?

$T_m$ denotes the number of triangles that can be formed with the vertices of a regular polygon of $m$ sides. If $T_{m+1}-T_m=15$,then $m$ is equal to

If the number of diagonals of a regular polygon is $35$,then the number of sides of the polygon is

Some couples participated in a mixed doubles badminton tournament. If the number of matches played,such that no couple played in a match,is $840$,then the total number of persons who participated in the tournament is $........$.

If a polygon of $n$ sides has $275$ diagonals,then $n$ is