((e^x - e^(- x))／sin(x))
= ((e^x - 1) - (e^(- x) - 1))／sin(x))
= ((((e^x - 1) - (e^(- x) - 1))／x)／(sin(x)／x))
= (((e^x - 1)／x + (e^(- x) - 1)／(- x))／(sin(x)／x))
→ (1 + 1)／1
= 2