Răspuns:
F= F2 - F1
F= 7-12= - 5N
R rezultanta
R(vect.) = F (vect.) + F3 (vect.)
R^2= F^2 + F^3 + 2F x F^3 cos
R^2= (-5^2) + 5^2 + 2 x 5 x 5cos
25+25+50cos 120°
50+50° - (1/2) = 50-25=25
R=rad25=5N
(^n=la puterea)
