[حـلآتي بـ:هـدوئي..~]

Three forces act on a particle that moves with unchanging velocity v=(2 m\s)i -(7 m\s)j.Two of the forces are
f1=(2N)i+(3N)j+(-2N)k and f2=(-5N)i+(8N)j+(-2N)k.
? What is the third force



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