For real values of A, K cannot lie between [NDA-I 2020]

Correct Answer is : 131/331 and 3

Correct Answer is : 131/331 and 3

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UPSC NDA I and II 2020 Math Solved Paper

DIRECTIONS (Qs. 34-35) : Read the following information and answer the two items that follow:

Let

\frac{\tan 3A}{\tan A}=K,

where

\tan A \neq 0

and

K \neq \frac{1}{3}

[NDA-I 2020]

Question : 35 of 120

Marks: +1, -0

For real values of

\tan A, K

cannot lie between

Solution: 👈: Video Solution

We have,

\tan^{2} A = \frac{k-3}{3k-1}

For real values of

\tan^{2} A

\frac{K-3}{3K-1} \geq 0

\text{At } k = \frac{1}{3} \text{ and } 3, \frac{K-3}{3K-1} < 0

\therefore

For real values of

\tan A, K

cannot lie between

\frac{1}{3}

and 3

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