1/(sinx)^2 - 1/x^2 = [x^2 - (sinx)^2]/[xsinx]^2= [x^2 - (sinx)^2]/x^4*x^2/[sinx]^2lim_{x->0}[1/(sinx)^2 - 1/x^2]= lim_{x->0}[x^2 - (sinx)^2]/x^4*x^2/[sinx]^2= lim_{x->0}[x^2 - (sinx)^2]/x^4= lim_{x->0...