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Calculati aria trunghiului ABC daca B=4 ,BC=5 si m(B)=120 de grade.Dau coroana:D


Răspuns :

A=(AB.BC.sin B)/2=4.5.√3/2.1/2=
5√3
sin120=sin(60+60)=sin60cos60+sin60cos60=2*1/2*3/2=3/2
A=1/2*AB*BC*sin120=1/2*4*5*√3/2=5√3 cm2