The car shown in the Figure below is pulled by the force FA and FB. Force FA has a magnitude of 50kN.?

[HSB]

a) Find the magnitude and direction FB, if the resultant for FR is directed along the x-axis and θ = 45°.
b) Find the value of θ for which FB is minimum if the resultant for FR is 80kN
http://imageshack.us/photo/my-images/9/s...3at800.png

[billrussell42]

So the vector sum of Fa and Fb has to lie in the x axis, which means the y components have to add up to zero. or, the y components have to be equal.

Fay = 50k sin 20 = 17.1k
Fby = Fb sin 45 = 17.1
Fb = 17.1 / sin 45 = 24.2 kN. Direction is –45º as is stated

b) Fa = 50k, Fr = 80k
not enough info to solve.