Q) If tan θ = \frac{1}{\sqrt7}, then show that  = \frac {\csc^2 \theta - \sec^2 \theta}{\csc^2 \theta + \sec^2 \theta} = \frac{3}{4}

Ans: Given that, tan θ = \frac{1}{\sqrt7}

\therefore   cot θ = √7

Let’s start from numerator of LHS:

cosec2 θ – sec2 θ = (1 + cot2 θ) – (1 + tan2 θ)

= cot2 θ – tan2 θ

= (√7)2(\frac{1}{\sqrt 7})^2

= 7 – \frac{1}{7}

= \frac{48}{7} ………………… (i)

Similarly, let’s solve denominator of LHS:

cosec2 θ + sec2 θ

= (1 + cot2 θ) + (1 + tan2 θ)

= 2 + cot2 θ + tan2 θ

= 2 + (\sqrt 7)^2 + (\frac{1}{\sqrt 7})^2

= 9 + \frac{1}{7}

= \frac{64}{7} ………………….. (ii)

Now, let’s put the values from equation (i) and equation (ii) in LHS, we get:

LHS = \frac {\frac{48}{7}}{\frac{64}{7}}

= \frac {48}{64}

= \frac {3}{4}….. RHS….  Hence Proved !

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