Q: Draw ray AB starting at A through B. Name the angle formed by rays PQ and PR. Classify 90°, 120°. Ray AB: starts at A, passes through B, goes forever. Angle: ∠QPR (vertex P, arms PQ, PR). 90°: right angle. 120°: obtuse (> 90°, < 180°). Acute < 90°, straight = 180°, reflex > 180°!