Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
수학에서 평행부호는 두 선이 평행하다는 것을 나타냅니다.suhakeseo pyeonghaengbuho-neun du seon-i pyeonghang-hadaneun geos-eul natanabnida.In mathematics, the parallel sign indicates that two lines are parallel.