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GeoGebraGeoGebra Classroom

Inscribed quadrilateral and eccentric angles

Analysis 1

Change the positions of points A, O or V and note the angles and the sums. What can you notice?

Proof

Internal Eccentric Angle

Analysis 2

Enable the "Show / Hide central angles" and "Show / Hide the half sum of angles" boxes. Change the positions of points A, C or B and compare the inner eccentric angle with the result of the half sum. What can you notice?

Proof

External Eccentric Angle

Analysis 3

Enable the "Show /Hide central angles" and "Show / Hide half of the absolute value of the angle difference "boxes. Change the positions of points A, B, C or D and compare the external eccentric angle with the result of the difference. What can you notice?

Challenge

Explain the property.