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Bonjour,
[tex]cos(\widehat{ABC})=\dfrac{AB}{BC}\\\\cos(50^o)=\dfrac{6}{BC}\\\\BC\times cos(50^o)=6\\\\BC=\dfrac{6}{cos(50^o)}\\\\BC\approx 9,3\ cm[/tex]
[tex]cos(\widehat{ABC})=\dfrac{AB}{BC}\\\\cos(50^o)=\dfrac{6}{BC}\\\\BC\times cos(50^o)=6\\\\BC=\dfrac{6}{cos(50^o)}\\\\BC\approx 9,3\ cm[/tex]