Ключевые слова: abstract, area, arrow, art, background, center, circle, circles, circular, circumference, color, colorful, contour, design, diameter, distance, drawing, education, filled, flat, geometric, geometry, globe, icon, illustration, isolated, line, linear, lineart, math, mathematics, measure, outline, pi, point, radial, radius, round, science, sign, simple, sphere, symbol, technology, vintage, web,