**Problem: **If A, B, C are the angles of a triangle, then show that

**Discussion:**

We apply Jensen’s Inequality and Arithmetic Mean – Geometric Mean inequality here. Since cosine function is concave in the interval , we have

This implies

## Chatuspathi:

**What is this topic:**Properties of triangle**What are some of the associated concept:**Jensen Inequality, Arithmetic Mean-Geometric Mean Inequality**Where can learn these topics:**Cheenta**Book Suggestions: ‘**Secrets in