Solución

a.   $1.98669331$  

b.   $1.99986667$  

c.   $1.99999867$  

d.   $1.99999999$  

e.   $1.98669331$  

f.   $1.99986667$  

g.   $1.99999867$  

h.   $1.99999999$   $\mathop {\lim }\limits_{x \to 0} {{sen\left( {2x} \right)} \over x} = 2$