Math, asked by rishitoshmohantyall, 4 months ago

cosA-sinA÷cosA+sinA=sec2A- tan2A​

Answers

Answered by jozishaikh403
1

Answer is in the image

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Answered by riya15042006
2

 \frac{cos A - sin A}{cosA  + sinA}  = secA \:  - tanA

RHS :-

sec 2A - tan2A

 -  >  \frac{1}{cos2A} -   \frac{sin2 A}{cos2A}

 -  >  \frac{1 - sin2 A}{cos2A}

 -  >  \frac{1 - (2sinA \: cosA)}{( {cos}^{2} A -  {sin}^{2} A)}

 -  >  \frac{1 - 2sinA \: cosA}{ {cos}^{2} A -  {sin}^{2}A}

 -  >   \frac{{cos}^{2} A +  {sin}^{2}A - 2sinAcosA}{ {cos}^{2}A -  {sin}^{2} A }

[Putting \:  {cosA  }^{2}  +  {sin}^{2} A \:  in \:  place  \: of  \: 1 \:  because \: {cosA  }^{2}  +  {sin}^{2} A \:  = 1 ]

 -  >   \frac{ {(cosA - sinA)}^{2} }{(cosA - sinA)(cosA  +  sinA)}

[ Since  \:  {a}^{2}  +  {b}^{2}   - 2ab =  {(a + b)}^{2} and \:  {a}^{2} -  {b}^{2}   = (a  - b)(a + b)]

 -  >   \frac{(cosA - sinA)(cosA - sinA)}{(cosA - sinA)(cosA  + sinA)}

[ Since  \:  {a + b}^{2} = (a + b)(a + b) ]

 -  >  \frac{cosA - sinA}{cosA  +  sinA}

So , LHS = RHS

Hence Proved !!!

I hope it helps u dear friend ^_^

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