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**1. The problem statement, all variables and given/known data**

Find lim sin4x/3x

x -> 0

**2. Relevant equations**

**3. The attempt at a solution**

I did some algebraic massaging and got

sin4/3x = 4/4 * sin4x/3x = 4/3 * sin4x/4x

but I don't understand how sin4x/4x becomes 1 like my text book says so.