Variables in (pi)r^2 and 2(pi)r

• Lines from a circle's centre
• Pizza cut edges, e.g
• Lines from the centre to the circumference of a circle
• Two make the diameter
• Half-diameters
• Rim-to-hub lines
• Spokes of a wheel
• Euclid's arms?
• Parts of circles

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Radius \Ra"di*us\ (r[=a]"d[i^]*[u^]s), n.; pl. L. Radii (r[=a]"d[i^]*[imac]); E. Radiuses (r[=a]"d[i^]*[u^]s*[e^]z). [L., a staff, rod, spoke of a wheel, radius, ray. See Ray a divergent line.] (Geom.) A right line drawn or extending from the center of ...