Based on the answer choices, replace the pair of given values and verify the equation, as follow:
For x = π/4, π/6
the previous result means that the given values of x are not solution. The answer must be equal to zero.
Next, for x = 0, π
For both values of x the question is verified.
The rest of the options include π/4 and π/3 as argument, you have already shown that these values of x are not solution.
Hence, the solutions for the given equation are x = 0 and π