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The value of sec⁡2(tan⁡−12)+cosec2(cot⁡−13)\sec^2(\tan^{-1}2) + cosec^2(\cot^{-1}3) is:

Solution

✅ Correct Option: 4

Let θ1=tan⁡−12\theta_1 = \tan^{-1}2, so tan⁡θ1=2\tan\theta_1 = 2. Then sec⁡2θ1=1+tan⁡2θ1=1+4=5\sec^2\theta_1 = 1 + \tan^2\theta_1 = 1 + 4 = 5.

Let θ2=cot⁡−13\theta_2 = \cot^{-1}3, so cot⁡θ2=3\cot\theta_2 = 3. Then cosec2θ2=1+cot⁡2θ2=1+9=10cosec^2\theta_2 = 1 + \cot^2\theta_2 = 1 + 9 = 10.

Sum =5+10=15= 5 + 10 = 15.

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