1.Given equally spaced points on the circumference of a circle(the vertices of a regular n-gon).Find number of ways to select three points such that the triangle formed by joining them is isosceles.

2.Find number of ways to select 3 vertices from a polygon of sides 2n+1 such that the centre of the polygon lies inside the triangle.

3.An operation on a set is said to be binary,if ,for all , and it is said to be commutative if for all .Now if then find the following

(i)Total number of binary operations on

(ii)Total number of binary operations on such that

(iii)Total number of binary operations on such that