Proof without words: limit of sin(3x)/sin(x) as x→0

① This GeoGebra example visually demonstrates that the limit of sin(3x)/sin(x) as x approaches 0 equals 3, using a purely geometric construction without any verbal or algebraic explanation. ② The core mathematical concepts involve trigonometric limits, the relationship between angles and sine segments in the unit circle, and using geometric similarity or area ratios to approximate the limit. ③ Construction highlights: based on the summary, the example employs GeoGebra commands such as Segment, Circle, Rotate, Angle, Intersect, Midpoint, and Vector, creating multiple points (A, C, B, D, etc.), angles (α, β, γ, etc.), and auxiliary objects (f, c, d, g, h, i, j, M_α, δ, ε, ζ) to dynamically adjust the angle and observe the ratio change. ④ It is suitable for advanced high school or early college calculus students, serving as an intuitive introduction to limits and as a classroom demonstration tool to break through the abstraction of 'proof without words'.