How to Derive the Thin Lens Equation (1/d_o)+(1/d_i)=(1/f)

Please note:

This derivation is not fundamental, but it is more intuitive.

If you identify two equal angles in two different triangles as shown,
those triangles are similar (each correspondent side has the same ratio).

How to Derive the Thin Lens Equation (1/do)+(1/di)=(1/f)