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Question Number 155776 by mathdanisur last updated on 04/Oct/21
if   x∈(0;(π/2))  then prove that:  ((2 + (1+cotx)(tan^3 x+cot^3 x))/((1+tanx)(1+cotx))) ≥ (3/2)
$$\mathrm{if}\:\:\:\mathrm{x}\in\left(\mathrm{0};\frac{\pi}{\mathrm{2}}\right)\:\:\mathrm{then}\:\mathrm{prove}\:\mathrm{that}: \\ $$$$\frac{\mathrm{2}\:+\:\left(\mathrm{1}+\mathrm{cot}\boldsymbol{\mathrm{x}}\right)\left(\mathrm{tan}^{\mathrm{3}} \boldsymbol{\mathrm{x}}+\mathrm{cot}^{\mathrm{3}} \boldsymbol{\mathrm{x}}\right)}{\left(\mathrm{1}+\mathrm{tan}\boldsymbol{\mathrm{x}}\right)\left(\mathrm{1}+\mathrm{cot}\boldsymbol{\mathrm{x}}\right)}\:\geqslant\:\frac{\mathrm{3}}{\mathrm{2}} \\ $$

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