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MHT CET · Maths · Trigonometric Ratios & Identities

If \(p=\tan 20^{\circ}\), then value of \(\frac{\tan 160^{\circ}-\tan 110^{\circ}}{1+\tan 160^{\circ} \tan 110^{\circ}}\), in terms of \(p\) is

  1. A \(\frac{1+p^2}{2 p^2}\)
  2. B \(\frac{1+p^2}{2 p}\)
  3. C \(\frac{1-p^2}{2 p}\)
  4. D \(\frac{1-p^2}{2 p^2}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{1-p^2}{2 p}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \frac{\tan 160^{\circ}-\tan 110^{\circ}}{1+\tan 160^{\circ} \cdot \tan 110^{\circ}}=\tan \left(160^{\circ}-110^{\circ}\right)=\tan 50^{\circ} \\ & =\tan \left(90^{\circ}-40^{\circ}\right)=\cot 40^{\circ}=\frac{1}{\tan 40^{\circ}} \\ & =\frac{1}{\frac{2 \tan _2 0^{\circ}}{1-\tan ^2 20^{\circ}}}=\frac{1-\tan ^2 20^{\circ}}{2 \tan 20^{\circ}}=\frac{1-p^2}{2 p}\end{aligned}\)