Question

vetor resultante de a=5 ,b=8,cos= 120° =-0,5

Answer 1

Vr = a^2 + b^2 - 2*a*b*Cos120¤
Vr = (5)^2 + (8)^2 - 2*5*8*Cos120¤
Vr = 25 + 64 - 10*8*- 0,5
Vr = 89 + 80*0,5
Vr = 89 + 40
Vr = 129 u