Question

which labelled part of the diagram represents the focal length​

Answer 1

Answer:

in any diagram of curved lens and mirrors there is a focal length, from the pole to the principal focus is the focal length of curved mirrors and in lens , F1 to the optical centre is the focal length

and plz attach the diagram for the proper answer you want . But I guess this might help you to find. it

Answer 2

Where is the diagram ??