A person 1.70 m tall stands 2.0 m in front of a plane mirror. (a) Where is the image and how tall is it? (b) What minimum mirror height is needed to see the full body? (c) If the person walks 1.0 m toward the mirror, how far does the image move? Step 1: Image is virtual, upright, same size (1.70 m), and 2.0 m behind the mirror. Distance between person and image = 4.0 m. Step 2: By similar triangles, the mirror need cover only from eye level to halfway between eye and feet: minimum height = 1.70/2 = 0.85 m, with its top at eye height (~1.60 m) — independent of the 2.0 m distance! Step 3: Person now 1.0 m in front; image 1.0 m behind. The image moved 2.0 m toward the person (twice the person's movement) — image speed is double when approaching a plane mirror. Person–image distance is now 2.0 m.