I have been solving for a long time but in my answer my LHS is not equal to RHS....therefore pls help me....

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- Sep 30th 2009, 11:16 AMSanjana DasProve that :-

I have been solving for a long time but in my answer my LHS is not equal to RHS....therefore pls help me.... - Sep 30th 2009, 11:33 AMSanjana Das
do not solve plss its a totally wrong quest.

- Sep 30th 2009, 11:36 AMSanjana Das
corrected question

I have been solving for a long time but in my answer my LHS is not equal to RHS....therefore pls help me.... - Sep 30th 2009, 11:46 AMSanjana Das
No need to solve i have solved............(Thinking)

- Sep 30th 2009, 03:09 PMDeMath
You have

Now simplify the left side by formula left side and transform

Now estimate the sum .

If , then .

Since the cosine function in the interval positive and negative in , it follows that ,

ie you have

Thus, the initial equality is proved.