## Triangle(a,b,c); a^2, b^2, c^2 and cot of interior angles are in A.P.

Let   $(a, \; b, \; c)$   be the sides of triangle such that   $a^2, \; b^2, \; c^2$   are in A.P.

$a^2 \; + \; c^2 \; = \; 2 \, b^2$

Prove that the cotangent of the interior angles are also in A.P.