How many triangles can be formed by joining four points on a circle?

If $5$ parallel lines are intersected by $4$ parallel lines,then what is the number of parallelograms formed?

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

Among $10$ points in a plane,no three points are collinear and $4$ points are concyclic. How many distinct circles can be drawn using at least $3$ of these points?

There are $10$ points in a plane of which no three points are collinear except $4$ points. The number of distinct triangles that can be formed by joining these points such that at least one of the vertices of every triangle formed is from the given $4$ collinear points is:

$A$ polygon has $54$ diagonals. The number of sides of this polygon is