Cercle trigonométrique
The unit circle is the bridge between triangle trigonometry and the sine and cosine waves. This simulation walks a point round the circle while plotting its coordinates, showing exactly where those waves come from.
Comment utiliser cette simulation
- Sweep the angle around the circle
- Read the coordinates as sine and cosine values
- Switch between degrees and radians
Ce qu’il faut observer
- The x-coordinate traces a cosine curve and the y-coordinate a sine
- Both functions repeat exactly once per full revolution
- Signs flip quadrant by quadrant, matching the coordinate signs
La physique derrière
A point on the unit circle at angle θ has coordinates (cosθ, sinθ). Sweeping θ traces out both functions, which explains why they repeat every 2π and why they are bounded by ±1. It also explains the signs in each quadrant, and gives meaning to angles beyond 90°, where no right triangle exists.