Ключевые слова: 2d, abstract, algebra, analysis, book, calculation, chart, coordinate, coordinates, cotangent, ctg, curve, data, drawing, education, exercise, figure, formula, function, graph, graphic, grid, layout, line, marking, math, mathematics, matrix, note, paper, periodic, periodical, physics, schedule, scheme, school, science, sheet, sign, square, study, symbol, table, technical, template, trigonometry, value, wave, wavy,