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Update 12.temporary_ins/71.waves/30.n3/25.interferences-by-wavefront-division/20.overview/cheatsheet.fr.md

Update 12.temporary_ins/71.waves/20.n2/15.interferences-two-harmonic-synchrone-waves/20.overview/cheatsheet.fr.md

Update 12.temporary_ins/90.electromagnetism-in-vacuum/10.maxwell-equations/20.overview/cheatsheet.fr.md