Problem
GEO-B1-M05-P002 One Chord
#2
★☆☆☆☆ Level 1 of 5
Points \(A,B,C,D\) lie on one circle, and \(B\) and \(D\) are on the same side of chord \(AC\). Prove that \(\angle ABC=\angle ADC\).
Both angles stand on chord \(AC\).
Angles \(\angle ABC\) and \(\angle ADC\) are inscribed and stand on the same chord \(AC\). With the given position, they look at the same arc \(AC\), so they are equal.
This is the main pattern of the module; it should be revisited many times.