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The value of tan⁡2(sec⁡−12)+cot⁡2(cosec⁡−13)\tan^2(\sec^{-1} 2) + \cot^2(\cosec^{-1} 3) is equal to

Solution

✅ Correct Option: 2

Let θ=sec⁡−12\theta = \sec^{-1} 2

This means sec⁡θ=2\sec \theta = 2

Since sec⁡θ=1cos⁡θ\sec \theta = \frac{1}{\cos \theta}:

cos⁡θ=12\cos \theta = \frac{1}{2}

Using the identity sec⁡2θ−tan⁡2θ=1\sec^2 \theta - \tan^2 \theta = 1:

tan⁡2θ=sec⁡2θ−1\tan^2 \theta = \sec^2 \theta - 1

tan⁡2θ=(2)2−1\tan^2 \theta = (2)^2 - 1

tan⁡2θ=4−1\tan^2 \theta = 4 - 1

tan⁡2θ=3\tan^2 \theta = 3


Let ϕ=cosec⁡−13\phi = \cosec^{-1} 3

This means cosec⁡ϕ=3\cosec \phi = 3

Since cosec⁡ϕ=1sin⁡ϕ\cosec \phi = \frac{1}{\sin \phi}:

sin⁡ϕ=13\sin \phi = \frac{1}{3}

Using the identity cosec⁡2ϕ−cot⁡2ϕ=1\cosec^2 \phi - \cot^2 \phi = 1:

cot⁡2ϕ=cosec⁡2ϕ−1\cot^2 \phi = \cosec^2 \phi - 1

cot⁡2ϕ=(3)2−1\cot^2 \phi = (3)^2 - 1

cot⁡2ϕ=9−1\cot^2 \phi = 9 - 1

cot⁡2ϕ=8\cot^2 \phi = 8


tan⁡2(sec⁡−12)+cot⁡2(cosec⁡−13)=3+8\tan^2(\sec^{-1} 2) + \cot^2(\cosec^{-1} 3) = 3 + 8

=11= 11

Therefore, the value is 1111.

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