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Mathematics

tan θsec θ - 1+tan θsec θ + 1\dfrac{\text{tan θ}}{\text{sec θ - 1}} + \dfrac{\text{tan θ}}{\text{sec θ + 1}} is equal to :

  1. 2 cosec θ

  2. 2 sec θ

  3. 2 tan θ

  4. sec θ tan θ

Trigonometric Identities

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Answer

Solving,

tan θsec θ - 1+tan θsec θ + 1tan θ(sec θ + 1) + tan θ(sec θ - 1)(sec θ - 1)(sec θ + 1)tan θ. sec θ + tan θ + tan θ.sec θ - tan θsec2θ12 tan θ. sec θ tan 2θ2 sec θtan θ2×1cos θsin θcos θ2×1cos θ×cos θsin θ2sin θ2 cosec θ.\Rightarrow \dfrac{\text{tan θ}}{\text{sec θ - 1}} + \dfrac{\text{tan θ}}{\text{sec θ + 1}} \\[1em] \Rightarrow \dfrac{\text{tan θ(sec θ + 1) + \text{tan θ(sec θ - 1)}}}{\text{(sec θ - 1)(sec θ + 1)}} \\[1em] \Rightarrow \dfrac{\text{tan θ. sec θ + tan θ + tan θ.sec θ - tan θ}}{\text{sec}^2 θ - 1} \\[1em] \Rightarrow \dfrac{\text{2 tan θ. sec θ}}{\text{ tan }^2 θ} \\[1em] \Rightarrow \dfrac{\text{2 sec θ}}{\text{tan θ}} \\[1em] \Rightarrow \dfrac{2 \times \dfrac{1}{\text{cos θ}}}{\dfrac{\text{sin θ}}{\text{cos θ}}} \\[1em] \Rightarrow \dfrac{2 \times \dfrac{1}{\text{cos θ}} \times \text{cos θ}}{\text{sin θ}} \\[1em] \Rightarrow \dfrac{2}{\text{sin θ}} \\[1em] \Rightarrow \text{2 cosec θ}.

Hence, Option 1 is the correct option.

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