URL：https://static.vecteezy.com/system/resources/previews/007/265/952/large_2x/happy-pi-day-celebrate-pi-day-mathematical-constant-march-14th-ratio-of-a-circle-s-circumference-to-its-diameter-constant-number-pi-illustration-vector.jpg
掲載元：https://www.vecteezy.com/vector-art/7265952-happy-pi-day-celebrate-pi-day-mathematical-constant-march-14th-ratio-of-a-circle-s-circumference-to-its-diameter-constant-number-pi-vector-illustration
