Left: Jump and climb.
This secret is ultimately lost if Lara enters the timed exit door (room with 3 doors and spikes - end level)
Right: Near the ladder end: climb all left: observe the (emphatized) Lara's shadow on the small sloped triangular ledge. Release Lara holding the jump key: Lara shall land near the Green Dragon.
Both the standard backflip and the more sophisticated backflip-roll-and-grab seem useless here.