1. $cos2x-1=-2sin^22x$$\frac{-(2x)^2(\frac{sin2x}{2x})^2}{(3x)^2(\frac{sin3x}{3x})^2} \frac{-4}{9}2.\frac{sinx(1-cosx)}{x^3cosx}=\frac{sinx.sin^2\frac{x}{2}}{x.(\frac{x}{2})^2.2} \frac{1}{2}$
1. cos2x−1=−2sin2x$\frac{-2.(x)^2(\frac{sinx}{x})^2}{(3x)^2(\frac{sin3x}{3x})^2} \frac{-2}{9}2.\frac{sinx(1-cosx)}{x^3cosx}=\frac{sinx.sin^2\frac{x}{2}}{x.(\frac{x}{2})^2.2} \frac{1}{2}$