Question

f1=100N, f2=150N, góc a=120, f3=50N. Tính độ lớn hợp lỰc F

Answer 1

(F1;F2) =120^o

\(F=\sqrt{F_1^2+F_2^2+2F_1F_2cos\alpha}=\sqrt{100^2+150^2+2.100.150.cos120}=50\sqrt{7}\left(N\right)\)

(F2;F3) =120^o

\(F'=\sqrt{F_2^2+F_3^2+2F_2F_3cos\alpha}=\sqrt{150^2+50^2+2.150.50.cos120}=50\sqrt{7}\left(N\right)\)=> \(F_{hl}=\sqrt{F^2+2F.F'cos120+F'^2}=50\sqrt{7}\left(N\right)\)