The equation esin⁡x−e−sin⁡x=4 has:

Put esin⁡x=y. Note that 1/e≤y≤e.Also, the given equation can be written as            y−1/y=4 or y2−4y−1=0⇒       y=2±5.As 1/e≤y≤e, none of the two values of y is possible.