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 \[{{(81)}^{{{\sin }^{2}}\pi /6}}+{{(81)}^{{{\cos }^{2}}\pi /6}}=30\] \[\Rightarrow \,\,{{(81)}^{1/4}}+{{(81)}^{3/4}}=30\Rightarrow 30=30\]You need to login to perform this action.
You will be redirected in
3 sec