In-a-triangle-ABC-prove-the-following-a-b-c-2-a-2-b-2-c-2-cot-A-2-cot-B-2-cot-C-2-cot-A-cot-B-cot-C-

Question Number 10947 by rish@bh last updated on 03/Mar/17

In a triangle ABC prove the following

\frac{{(a + b + c)}^{2}}{a^{2} + b^{2} + c^{2}} = \frac{\cot \frac{A}{2} + \cot \frac{B}{2} + \cot \frac{C}{2}}{\cot A + \cot B + \cot C}