Ключевые слова: acute, angle, background, black, blackboard, centimeter, chalk, chalkboard, closeup, college, color, degrees, design, drafting, drawing, drawn, education, engineering, equipment, flat, geometry, item, knowledge, lay, learning, length, line, markings, math, mathematics, measure, measuring, number, object, protractor, ruler, school, science, shape, stationery, study, supplies, table, teach, tool, top, triangle, university, view, work,