Angles at the Circle

This app is about angles at the circle. The following terms and their properties are illustrated:

The central angle (blue) can be increased or decreased by using the slider. By dragging with pressed mouse button you can vary the vertex of the inscribed angle (red).

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  1. Inscribed angles intercepting the same arc have the same measure.
  2. The measure of any inscribed angle is half the measure of the corresponding central angle.
  3. The angles between a chord and a tangent have the same meausure as an inscribed angle and half the measure of the central angle.