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  • Utilisateur Brainly
2013-06-09T09:22:15+02:00

ex 1:

a) ABC est rectangle en A

cos(ABC)=AB/BC

sin(ABC)=AC/BC

tan(ABC)=AC/AB

 

b) donc d'apres le th de Pythagore : AB²+AC²=BC²

 

c) cos²(ABC)=AB²/BC²

sin²(ABC)=AC²/BC²

 

donc cos²(ABC)+sin²(ABC)=AB²/BC²+AC²/BC²

                                                 =(AB²+AC²)/BC²

                                                 =BC²/BC²

                                                 =1

 

d) sin(ABC)/cos(ABC)=(AC/BC)/(AB/BC)

                                       =AC/BC*BC/AB

                                       =AC/AB

                                       =tan(ABC)

 

ex 2:

a) √48=√(16*3)=√16*√3=4√3

donc A=4√48+8√3

            =4*4√3+8√3

            =24√3

 

b) B=14x²-9x-18

si x=√2 alors B=14*2-9√2-18

                           =28-9√2-18

                           =10-9√2

 

c) C=3√2(√3+1)+(√2-1)(√2-2)

       =3√6+3√2+2-√2-2√2+2

       =3√6+4

 

ex 3:

exercice TRES simple de Statistiques descriptives...

(laissé au lecteur)