In Syzran vandals started to behave unusually. Locals are surprised. On metal wall of bus stop unknowns wrote math formulas instead of usual scribbles and obscene texts.
It is possible author of message was memorizing trigonometric functions or even explaining other person with help of black marker. In any case he[author] managed to surprise people waiting for bus.
Even though writing on bus stop is not welcomed, vandals started to move in right direction. Knowledge is the light in darkness of ignorance.
Source: https://ktv-ray.ru/novost/uchene_-_svet_syzranskie_vandaly_raspisali_ostanovku_trigonometricheskimi_funkciyami/137091/