What is d-a/b-d equal to? [NDA-I 2020]

Correct Answer is : tan⁡2y² ytan2y

Correct Answer is : tan⁡2y² ytan2y

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UPSC NDA I and II 2020 Math Solved Paper

DIRECTIONS (Qs. 16-18) : Read the following information and answer the three items that follow:

Let

a \sin^{2} x + b \cos^{2} x = c ; b \sin^{2} y + a \cos^{2} y = d

and

p \tan x = q \tan y

[NDA-I 2020]

Question : 17 of 120

Marks: +1, -0

What is

\frac{d-a}{b-d}

Solution: 👈: Video Solution

From

b \sin^{2} y + a \cos^{2} y = d

b \sin^{2} y + a \cos^{2} y

= d(\sin^{2} y + \cos^{2} y)

(b-d) \sin^{2} y = (d-a) \cos^{2} y

\Rightarrow \frac{\sin^{2} y}{\cos^{2} y} = \frac{d-a}{b-d}

\Rightarrow \tan^{2} y = \frac{d-a}{b-d}

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