Bonsoir,
1) Théorème de Pythagore : DF² = 34² - 16² = 900
donc : DF = √900 = 30 cm
2) cos angle DEF = DE/EF = 16/34 = 8/17
sin angle DEF = DF/EF = 30/34 = 15/17
tan angle DEF = DF/DE = 30/16 = 15/8
3) cos angle DFE = DF/EF = 30/34 = 15/17
tan angle DFE = DE/DF = 16/34 = 8/17
