Diameter halves

• Spokes of a wheel, essentially
• Bicycle spokes, essentially
• Lines on a pie chart, e.g
• Minute hands, say
• They form central angles
• Supporters-in-arms notice Republican units gathering
• Lines on sonar screens
• Some bones
• Pizza slice borders, e.g

Wiktionary Word definitions in Wiktionary
n. (plural of radius English)