- #1

## Homework Statement

A pole BC is supported by the cable AB as is shown in the figure. If the magnitude of the force applied on the point B is 70 lb, and the moment of this force about the x-axis is -763 lb ft, determine the pole lenght.

I'LL ATTACH AN IMAGE SO YOU CAN SEE IT.

## Homework Equations

τ= torque or moment of force

τ= r X F

Tτ= T1+T2

Tτ=(r1 + r2) x F

## The Attempt at a Solution

I don't know how to compute the lenght, I was thinking about it maybe was related with the torque or moment of force (let me know if this is true).

What I tried to do was this:

r1= 4i + 6k

e= 4i+6k

e=√4^2+6^2

e=√52

e=4/√52 + 6/√52

F= 70(4/√52 + 6/√52) = 38.82i+58.24k

and by performing the determinant

τ= -0.04 lb/ft

So far I should've got the T1 and now I'd do the same but this time with other vectors ⇒ 4i-6k

I don't think it's correct since I got a result on differents units that don't measure the lenght. PLEASE TRY TO TELL WHAT I'M WRONG AND WHAT I'M RIGHT.