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Prove the following identities: (cos theta cosec theta - sin theta sec theta )/(cos theta + sin theta) = cosec theta - sec theta

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Question

Prove the following identities:

`(cos theta  "cosec"  theta - sin theta sec theta )/(cos theta + sin theta) = "cosec"  theta - sec theta`

Theorem
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Solution

LHS = `(cos theta   cosec theta - sin theta  sec theta )/(costheta + sin theta)`

      =`((cos theta   sin theta)/(sin theta cos theta))/(cos theta + sin theta)`

      =`(cos^2  theta - sin^2 theta)/(cos theta  sin theta ( cos theta + sin theta))`

      =`((cos theta + sin theta )( cos theta - sin theta))/(cos theta sin theta ( cos theta + sin theta))`

      =`((cos theta - sin theta ))/(cos theta   sin theta)`

     =`1/ sin theta - 1/ cos theta`

     =`cosec theta - sec theta`

     = RHS
Hence, LHS = RHS 

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Chapter 13: Trigonometric identities - EXERCISE 13A [Page 618]

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R.S. Aggarwal Mathematics [English] Class 10
Chapter 13 Trigonometric identities
EXERCISE 13A | Q 28. | Page 618
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