What is $$\mathop {\lim }\limits_{x \to 0} {{\tan x} \over {\sin 2x}}$$ equal to

What is $$\mathop {\lim }\limits_{h \to 0} {{\sqrt {2x + 3h} - \sqrt {2x} } \over {2h}}$$ equal to ?

For what value of k is the function $$f(x) = \left\{ \matrix{ 2x + {1 \over 4},x < 0 \hfill \cr k,x = 0 \hfill \cr {\left( {x + {1 \over 2}} \right)^2},x > 0 \hfill \cr} \right.$$ continuous?

What is the value of $$\mathop {\lim }\limits_{x \to 0} {{\sin x^\circ } \over {\tan 3x^\circ }}$$ ?