Question

since, no condition is given yor ( x_{i} ), ( sum_{i=1}^{2 n} cos ^{-1} x_{i}=0 )
( Rightarrow cos ^{-1} x_{1}+cos ^{-1} x_{2}-cdots-cos ^{-1} x_{2 n}=0 )
if ( x_{1}=x_{2}=x_{3}-cdots=x_{2 n}=1 )
then all toms become ( 0^{prime} ) and equation is satisfied.
( 80, ) uce heme to find, ( sum_{i=1}^{2 n} 1=1+1+1--cdots 2 n ) times
( n )
So, requicred ansiolen is an

# 2 . 21. ΠΣ των " η -0, then. Στη 15 αφual to

Solution