Ключевые слова: angle, axes, calculation, center, cheat, circle, cosinus, design, devising, diagram, division, drawing, educational, example, explanation, formula, geometry, graphic, guide, info, law, learn, length, line, lines, logic, model, parts, points, proportion, radius, round, scheme, school, sheet, simple, sinus, size, structure, study, tangents, task, test, triangle, trigonometry, worksheet,