Problem

Problem

If α=3sin⁡−1(611)\alpha = 3 \sin^{-1} \left( \frac{6}{11} \right) and β=3cos⁡−1(49)\beta = 3 \cos^{-1} \left( \frac{4}{9} \right) , where the inverse trigonometric functions take only the principal values, then the correct option(s) is/are [More than one correct option, JEE 2015 Adv.] a. cos⁡β>0\cos \beta > 0 b. sin⁡β<0\sin \beta < 0 c. cos⁡(α+β)>0\cos(\alpha + \beta) > 0 d. cos⁡α<0\cos \alpha < 0

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