how to make the vertices of 2 lines coincide

[GULLUWING]

I have to make the vertices coincide at and c without changing the length of the lines ab and cd, keeping the points b and d as rotation axes.
Can you help me? I tried to use the command line but the two vertices while approaching I can never get them to meet

 

[GULLUWING]

I have solved.
Thanks and sorry

I have to make the vertices coincide at and c without changing the length of the lines ab and cd, keeping the points b and d as rotation axes.
Can you help me? I tried to use the command line but the two vertices while approaching I can never get them to meet

 

[Fulvio Romano]

I have solved.
Thanks and sorry

Maybe tell us how?

However it is resolved by making two circumferences and finding its intersection.