1.

Prove that cot θ-cosθ/cotθ+cosθ=cosecθ-1/cosecθ+1​

Answer»

ANSWER:

Step-by-step EXPLANATION:

\Large{\underline{\rm{Given:}}}

\sf \dfrac{cot\theta-<klux>COS</klux>\theta}{cot\theta+cos\theta} =\dfrac{cosec\theta-1}{cosec\theta+1}

\Large{\underline{\rm{To\:Prove:}}}

LHS = RHS

\Large{\underline{\rm{Identities\:used:}}}

\sf cot\theta=\dfrac{cos\theta}{sin\theta}

\sf \dfrac{1}{sin\theta} =cosec\theta

\Large{\underline{\rm{Proof:}}}

➞Here we have to the prove that the LHS of the equation = RHS.

➞ Taking the LHS of the equation,

    \sf \dfrac{cot\theta-cos\theta}{cot\theta+cos\theta}

➞ Using identities,

    \sf \implies \dfrac{\dfrac{cos\theta}{sin\theta}-cos\theta }{\dfrac{cos\theta}{sin\theta} +cos\theta}

➞  Taking cos θ COMMON from both numerator and denominator,

      \sf \implies \dfrac{cos\theta(\dfrac{1}{sin\theta}-1) }{cos\theta(\dfrac{1}{sin\theta} +1)}

➞ Cancelling cos θ on both numerator and denominator,

    \sf \implies \dfrac{(\dfrac{1}{sin\theta}-1) }{(\dfrac{1}{sin\theta} +1)}

➞  Using SUITABLE identities,

     \sf \implies \dfrac{cosec\: \theta -1}{cosec\: \theta+1}

     \implies \sf RHS

➞  Hence proved.

\Large{\underline{\rm{More\:Identities:}}}

\sf tan\theta=\dfrac{sin\theta}{cos\theta}

\sf \dfrac{1}{cos\theta} =sec\theta

\sf \dfrac{1}{tan\theta} =cot\theta



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