Wavelength measures the repeat of the pattern: crest to crest, trough to trough, or node to node. Doesn’t matter which one you choose, same results!
Crest to crest: 1.05 – 0.45 = 0.60m
Trough to trough: 0.75 – 0.15 = 0.60m
Node to node: 0.60 – 0 = 0.60m (or 0.90 – 0.30 = -.60m; or 1.2 – 0.60 = 0.60m)