Question

Ma ajuta cineva la problema asta?

Answer 1

Explicație pas cu pas:

A,O,C-puncte coliniare

<AOC=180°(1)

<BOC=120°(2)

(1),(2)=><AOB=60°

<ABO=80°(3)

<BOA=60°(4)

(3),(4)=><OAB=40°

∆BAD 1. BA=CD

}. 2.AD=BC. }=>∆BAD=∆DCB=>

∆DCB 3.<BAD=<BCD

=><BDC=<DBA=80°