Răspuns:
M ,A ,B -pct coliniare => <MAB =180°
A ,B ,N - pct coliniare => <ABN =180°
• AO = OB => <OAB=<OBA = <a
< MAB = <MAO+ < a = 180° ||
< ABN = <ABN+ <a = 180°. || => <MAO = <ABN 1.
MO =ON = R 2.
∆MON - ISOS. => < M = < N 3.
1. ||
2.||=> ∆MOA = ∆OBN => MA=BN
3.||
