f(x)=sin(x)df(x)≈f(x+Δx)-f(x)dx≈Δxdf(x)/dx≈{f(x+Δx)-f(x)}/Δxf(x+Δx)=(df(x)/dx)Δx+f(x)sin(45°+1°)=cos45°*1°+sin45° =√2/2+√2/2 =√2
