$\overrightarrow{P},\overrightarrow{Q},\overrightarrow{R},\overrightarrow{S}$ are vectors of equal magnitude. If $\overline{P}+\overline{Q}-\overline{R}=O$ angle between $\overline{P}$ and $\overline{Q}$ is ${\overline{\theta }}_1$ If $\overline{P}+\overline{Q}-\overline{S}=O$ angle between $\overline{P}$ and $\overline{S}$ is ${\theta }_2\text{. }$ The ratio of ${\overline{\theta }}_1\text{ to }{\theta }_2$ is