The voltage across the circuit in the figure, and the current through it, are given by the following expressions:

𝑣(𝑡) = 5 – 10 cos (𝜔𝑡 + 60°) V

𝑖(𝑡) = 5 + Xcos (𝜔𝑡) A

 where 𝜔 = 100𝜋 radian/s. If the average power delivered to the circuit is zero, then the value of X (in Ampere) is _____ (up to 2 decimal places).