Exercise $3\mathrm{.}12$

Differentiate the following:

a$.cos3x$

b$.sin(4x+5)$

c$.si{n}^{3}x$

d$.sinxcosx$

e$.x^{2}sinx$

f$.cos(x^2+1)$ g$.\frac{sinx}{x}$

h$.sin(\frac{1}{x})$

i$.tan(\sqrt[\phantom{2}]{x})$ j$.\frac{1}{x}sin(\frac{1}{x})$