Solution Insights: Problem on Inequalities for 27–01–2022

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image by author

This problem has a simple solution that requires the knowledge of two elementary facts — the geometric property of intersecting chords of a circle, and the relation between the Arithmetic Mean and the Geometric Mean of a set of numbers.

The first fact states that if AB and CD are two chords in a circle and intersect each other at P, then (AP)(PB) = (CP)(PD). From this, we get the first essential fact to solve this problem:

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The second fact states that the Arithmetic Mean of a set of numbers is always either greater than or equal to their Geometric Mean. Thus, we get the second essential fact to solve the problem:

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This directly leads us to the relation which we had wanted to prove,

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QED.

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