Let A₁, A₂,.....A_n be a regular n-sided polygon inscribed in a circle. Three points A_i, A_j, A_k are randomly chosen, where i,j,k are distinct integers between 1 and n, both inclusive. Denote by P_n the probability that the triangle A_iA_jA_k is obtuse, which of the following statements is/are true? 

Let A₁, A₂.....A_2n be the vertices of regular polygon of of n sides now select A₁ and the remaining vertices from the right hand side i.e ^(n–1)C₂
Similarly on the left hand side also ($\because$circum centre always lies out side the obtuse triangle) So required probability
$\frac{2\times 2\mathrm{n}\times {(\mathrm{n}-1)}_{{\mathrm{C}}_2}}{\frac{2}{2{\mathrm{n}}_{{\mathrm{C}}_3}}}$(here 2n is oven) or when n is odd
$\frac{2\left(\frac{\mathrm{n}-1}{2}\right){\mathrm{C}}_2\cdot \mathrm{n}}{2\left({ }^{\mathrm{n}}{\mathrm{C}}_3\right)}$