Question

已知三力f₁=(3,4),f₂=(2,-5),f₃=(x,y),f₁,f₂,f₃的合力为零,求力f₃的坐标（x,y）.

Answer 1

解：∵f₁+f₂+f₃=0，

∴f₃=-(f₁+f₂)

=-(3,4)-(2,-5)=(-5,1).