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CBSE Class 12 Math 2020 Outside Delhi Set 1 Solved Paper

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Section - A
Question numbers 1\mathbb{1} to 10\mathbb{10} are multiple choice questions of 1\mathbb{1} mark each. Select the correct option :
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Question : 1 of 36
Marks: +1, -0
The value of sin⁡−1(cos⁡3π5)\sin^{-1} \left(\cos \frac{3\pi}{5}\right) is
Solution:     👈: Video Solution
sin⁡−1(cos⁡33π5)=sin⁡−1(cos⁡(6π+3π5))\sin^{-1} \left(\cos \frac{33\pi}{5}\right) = \sin^{-1} \left(\cos \left(6\pi + \frac{3\pi}{5}\right)\right)
=sin⁡−1(cos⁡(3π5))= \sin^{-1} \left(\cos \left(\frac{3\pi}{5}\right)\right)
sin⁡−1(cos⁡(π2+π10))\sin^{-1} \left(\cos \left(\frac{\pi}{2} + \frac{\pi}{10}\right)\right)
=sin⁡−1(−sin⁡(π10))= \sin^{-1} \left(-\sin \left(\frac{\pi}{10}\right)\right)
∴sin⁡−1(cos⁡33π5)=−π10\therefore \sin^{-1} \left(\cos \frac{33\pi}{5}\right) = \frac{-\pi}{10}
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