1. A method for polygon gesture detection and interaction, adapted to an electronic apparatus having an input unit, and the method comprises: receiving a gesture moving from a starting point to an end point by using the input unit and collecting a plurality of sampling points from the starting point to the end point; analyzing a trajectory of the sampling points to obtain a center of the gesture; dividing, by using the center as an origin, a surrounding area of the origin into a plurality of equal label areas; calculating a distance and an angle relative to the origin of each of the sampling points in the label areas, and drawing a waveform diagram by using the distance as a vertical axis and using the angle as a horizontal axis; and determining a shape formed by the trajectory according to at least one characteristic of the waveform diagram, and performing a specific function corresponding to the shape.