If `A+B+C=pi,` prove that `tan^2(A/2)+tan^2(B/2)+tan^2(C/2)geq1.`

Explanation

To prove that \( \tan^2\left(\frac{A}{2}\right) + \tan^2\left(\frac{B}{2}\right) + \tan^2\left(\frac{C}{2}\right) \geq 1 \) given that \( A + B + C = \pi \), we can follow these steps:

### Step 1: Express \( C \) in terms of \( A \) and \( B \)
Since \( A + B + C = \pi \), we can express \( C \) as:
\[ C = \pi - A - B \]

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