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
여접은 삼각형의 두 변의 비율을 나타냅니다.yeojeob-eun samgak-hyeong-ui du byeon-ui biyul-eul natanabnida.The cotangent represents the ratio of the two sides of a triangle.