Respostas

2014-02-05T14:49:00-02:00
Resposta

Fr² = F1² + F² + 2.F1.F2.cos120º
Fr² = 10² + 20² + 2.10.20.(-0,5)
Fr² = 100 + 400 + 400.(-0,5)
Fr² = 500 - 200
Fr² = 300
Fr = √300
Fr = 17,3N