Please note question number 3 has summation from $1$ to $2n$.
This is what I tried for question number $2$. If I put $n=1$ , the summation for two $\arcsin = \pi$. This can only happen if both $\arcsin=\pi/2$ $\implies$ $ x_1 = x_2 =1$. Which would mean summation of $x$ from $1$ to $2n$ should be equal to $2n$. The answer given is $0$. Where am I wrong?
I couldn't understand where to start question 3 and 4. Some hints would go a long way. Thanks.
All three questions are based on the same concept of maximum value of $\arcsin x$ and $\arccos x$ which are $\pi/2$ and $\pi$.
In three, for example, the maximum value of left side can be $n\pi$ which is in right side, hence all $x_1,x_2,\cdots$ are $1$.