The sum of two forces $\overrightarrow P $ and $\overrightarrow Q $ is $\overrightarrow R $ such that $\left| {\overrightarrow R } \right| = \left| {\overrightarrow P } \right|$ . The angle $\theta $ (in degrees) that the resultant of 2${\overrightarrow P }$ and ${\overrightarrow Q }$ will make with ${\overrightarrow Q }$ is , ..............