– (Solution)

[by Neelanjan Mondal] At first use the inequality ,

, note that be equal to –,

must be equal to + and must be equal to . , that is for any acute angled triangle , put the values of , so we obtain ,

;

= =

= .

It is given that that is =

that is = .

So ,it is easy to say , .

So , we are done .

[Please note that , ]

Here , we have used a lemma (about the incircle , incenter…etc.) that is …

Note that = for any acute angled triangle , dividing by to the both sides , we get .

Now , = for the triangle .

Now we will express by the terms of .

so , = – ( = .That is equal to = .

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