How to calculate period of the sinusoidal graph?

Question

I want to calculate the period of the following graphs. I'm confused with the fact that 2π is after few cycles. And there are numbers 1,2... instead of π/2,π....

Answer 1

The period is given by $$ \frac{2\pi}{\textrm{How many repeated cycles you have until you hit }x=2\pi}. $$ For example, the first graph has 5 repeated cycles up until $2\pi$, so the period is $\dfrac{2\pi}{5}$.