How do I find the limit of #x/(sin3x)#?

1 Answer
Mar 7, 2018

# #

# "The answer is:" \qquad \qquad \qquad lim_{ x rarr 0 } x/sin(3x) \ = \ 1/3. #

Explanation:

# "I assume you mean limit, as" \ x \ "goes toward 0 (?). We can" #
# "proceed as follows. The idea is to try to take advantage of" #
# "the Fundamental Trig Limit:" \quad lim_{ A rarr 0 } sin(A)/A \ = \ 1." #

# "Proceeding:" #

# \qquad lim_{ x rarr 0 } x/sin(3x) \ = \ lim_{ x rarr 0 } 1/{ sin(3x)/x } #

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ = \ lim_{ x rarr 0 } 1/{ 3/3 cdot sin(3x)/x } #

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ = \ lim_{ x rarr 0 } 1/{ 3 cdot [ sin(3x)/{ 3 x } ] } #

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ = \ lim_{ x rarr 0 } 1/3 cdot 1/{ [ sin(3x)/ { 3 x } ] } #

# color{blue}{ "now use the Fundamental Trig Limit:" \quad lim_{ A rarr 0 } sin(A)/A \ = \ 1; } #
# color{blue}{ \qquad "and use it with" \ A \ = \ 3 x. \ \ "Continuing:" } #

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ = \ 1/3 cdot 1/{ [1] }#

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ = \ 1/3. #

# "This is our answer:" #

# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \quad lim_{ x rarr 0 } x/sin(3x) \ = \ 1/3. #