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