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Question: Answered & Verified by Expert
If $\mathrm{p}=\operatorname{cosec} \theta-\cot \theta$ and $\mathrm{q}=(\operatorname{cosec} \theta+\cot \theta)^{-1}$, then which
one of the following is correct?
MathematicsTrigonometric Ratios & IdentitiesNDANDA 2019 (Phase 1)
Options:
  • A $\mathrm{pq}=1$
  • B $\mathrm{p}=\mathrm{q}$
  • C $p+q=1$
  • D $\mathrm{p}+\mathrm{q}=0$
Solution:
1184 Upvotes Verified Answer
The correct answer is: $\mathrm{p}=\mathrm{q}$
& \mathrm{p}=\operatorname{cosec} \theta-\cot \theta \\
& \mathrm{q}=(\operatorname{cosec} \theta+\cot \theta)^{-1} \\
& \Rightarrow \frac{1}{q}=\operatorname{cosec} \theta+\cot \theta \\
& \text { We know, } \operatorname{cosec}^{2} \theta-\cot ^{2} \theta=1 \\
& \Rightarrow(\operatorname{cosec} \theta+\cot \theta)(\operatorname{cosec} \theta-\cot \theta)=1 \\
& \Rightarrow\left(\frac{1}{q}\right)(p)=1 \\
& \Rightarrow \mathrm{p}=\mathrm{q}
\end{aligned}
$$

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