Equillibrium: torque and net force

[henry3369]

Homework Statement

http://imgur.com/rWsNsmp

Homework Equations

net torque = 0
net force = 0

The Attempt at a Solution

Finding f₁ was easy.
f₁ = w_ladder + _person = 885.92 N
Then the horizontal forces are also equal:
f₂ = f₃

Now net torque = 0 (I'm using moment arm because there is no angle given):
f₃(3.8) = w_ladder(moment arm) + w_person(0.70)

I can't manage to figure out the moment arm. I'm not sure if 0.7 meters can be used because I think that is the moment arm for the force of the person only. No angles were given, all I know is that the distance from the bottom of the ladder to the center of mass of the ladder is 2 meters.

 

[Svein]

No angles were given

Oh, yes, they were (but indirectly). Length of ladder = 4m, vertical height of ladder = 3.8m.

 

[henry3369]

Oh, yes, they were (but indirectly). Length of ladder = 4m, vertical height of ladder = 3.8m.

Didn't think about it that way. Thanks!