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Ask iit jee aieee pet cbse icse state board community Community Discussion Question: Prove that-
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matsci (0)

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1/(cosecA-cotA) -1/sinA=1/sinA-1/(cosecA+cotA)

    
rudra.panda (2263)

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posting the solution........

God does not care about our mathematical difficulties. He integrates empirically. ~~~Albert Einstein (1879-1955)~~~~
To divide a cube into two other cubes, a fourth power or in general any power whatever into two powers of the same denomination above the second is impossible, and I have assuredly found an admirable proof of this, but the margin is too narrow to contain it.~~~Pierre de Fermat (1601-1665)~~~


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rudra.panda (2263)

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LHS=


\dfrac{1}{cosec A-cot A}-\dfrac{1}{\sin A}\\=\dfrac{\sin A}{1-\cos A}-\dfrac{1}{\sin A}\\=\dfrac{Sin A(1+\cos A)}{1-\cos^2A}-\dfrac{1}{\sin A}\\=\dfrac{1+ \cos A}{\sin A}-\dfrac{1}{ \sin A}\\=\dfrac{1+\cos A-1}{\sin A}\\=cot A


 


RHS=


\dfrac{1}{\sin A}-\dfrac{1}{cosec A + cot A}\\=\dfrac{1}{\sin A}-\dfrac{\sin A}{1+ \ cos A}\\=\dfrac{1}{\sin A}-\dfrac{1-\cos A}{\sin A}\\=\dfrac{1-1+\cos A}{\sin A}\\=cot A


As LHS=RHS so it is proved.


God does not care about our mathematical difficulties. He integrates empirically. ~~~Albert Einstein (1879-1955)~~~~
To divide a cube into two other cubes, a fourth power or in general any power whatever into two powers of the same denomination above the second is impossible, and I have assuredly found an admirable proof of this, but the margin is too narrow to contain it.~~~Pierre de Fermat (1601-1665)~~~


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Prajju (83)

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This question can be solved more easily by rearranging......
1/ (cosecA - cot A) - 1 / sinA = 1/ sin A - 1/ (cosec A + cot A)
==> 1/ (cosec A - cot A) + 1/ (cosec A + cot A) = 2/ sin A ----1
now taking LHS
{ [cosec A + cot A] + [cosec A - cot A] } / (cosec^2A - cot^2A)
==> 2cosec A / 1
==> 2 / sinA =RHS of eq. 1

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rudra.panda (2263)

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Great. Alternate ways are always welcomed.

God does not care about our mathematical difficulties. He integrates empirically. ~~~Albert Einstein (1879-1955)~~~~
To divide a cube into two other cubes, a fourth power or in general any power whatever into two powers of the same denomination above the second is impossible, and I have assuredly found an admirable proof of this, but the margin is too narrow to contain it.~~~Pierre de Fermat (1601-1665)~~~


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