91Ó°ÊÓ

The given statement is to explain that the period of the function is $180°$.

The definition of period or periodicity of a function means that the graph of a function repeats itself after a specific interval. Therefore, if the given function has a period of $180°$ then it means that the graph of the function repeats itself after an interval of $180{}^{∘}\text{or}\mathrm{π}$. For example, the period of the sine and cosine function is $360{}^{∘}\text{or}2\mathrm{π}$ which means that the graph of sine and cosine function will repeat after an interval of $360{}^{∘}\text{or}2\mathrm{π}$. And second example is of tangent and cotangent function whose period is $180{}^{∘}\text{or}\mathrm{π}$ which means that the period of tangent and cotangent function will repeat itself after an interval of $180{}^{∘}\text{or}\mathrm{π}$.

It means that the graph of the function repeats itself after an interval of $180{}^{∘}\text{or}\mathrm{π}$.