lim(x—>∞)(1—1/2^2)(1—1/3^2)……(1—1/n^2) =lim(x—>∞)(2^2-1)/2^2*(3^2-1)/3^2*...*(n^2-1)/n^2=lim(x—>∞)1/2*3/2*2/3*4/3*...*(n-1)/n*(n+1)/n=lim(x—>∞)1/2*(n+1)/n=1/2
