c) $\mathop {\lim }\limits_{x \to 0}\frac{1-cos^22x}{x.sinx}$= $\mathop {\lim }\limits_{x \to 0}\frac{sin^22x}{x.sinx}$=$\mathop {\lim }\limits_{x \to 0}\frac{(2x)^2.(\frac{sin2x}{2x})^2}{x^2.\frac{sinx}{x}}$= 4
c) $\mathop {\lim }\limits_{x \to 0}\frac{1-cos^22x}{x.sinx}$= $\mathop {\lim }\limits_{x \to 0}\frac{sin^22x}{x.sinx}$=$\mathop {\lim }\limits_{x \to 0}\frac{(2x)^2.(\frac{sin2x}{2x})^2}{x^2.\frac{sinx}{x}}$= 2
c) $\mathop {\lim }\limits_{x \to 0}\frac{1-cos^22x}{x.sinx}$= $\mathop {\lim }\limits_{x \to 0}\frac{sin^22x}{x.sinx}$=$\mathop {\lim }\limits_{x \to 0}\frac{(2x)^2.(\frac{sin2x}{2x})^2}{x^2.\frac{sinx}{x}}$=
4