A) \[\pi /6\]
B) \[\pi /2\]
C) \[\pi /4\]
D) \[3\pi /4\]
Correct Answer: A
Solution :
We have, \[{{81}^{{{\sin }^{2}}x}}+{{81}^{{{\cos }^{2}}x}}=30\] Now check by options, put \[x=\frac{\pi }{6}\] then \[{{(81)}^{{{\sin }^{2}}\pi /6}}+{{(81)}^{{{\cos }^{2}}\pi /6}}=30\] Þ \[{{(81)}^{1/4}}+{{(81)}^{3/4}}=30\] Þ 30 = 30 Hence A is the correct answer.You need to login to perform this action.
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