If $\alpha $ is an acute angle and $a,b\geq 0$ then show that: $\left( a+\frac{b}{\sin \alpha}\right)\left(b+\frac{a}{\cos \alpha}\right)\geq a^2+b^2+3ab$
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Tags: inequalities
If $\alpha $ is an acute angle and $a,b\geq 0$ then show that: $\left( a+\frac{b}{\sin \alpha}\right)\left(b+\frac{a}{\cos \alpha}\right)\geq a^2+b^2+3ab$