GATE2016-6

Question

Three currents $i_1, i_2$ and $i_3$ meet at a node as shown in the figure below. If $i_1=3\cos(\omega t)$ ampere, $i_2=4\sin(\omega t)$ ampere and $i_3=I_3\cos(\omega t+\theta)$ ampere, the value of $I_3$ in $\text{ampere}$ is $\_\_\_\_\_\_\_.$