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PensNAS

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## Homework Statement

Utility Pole BC is guyed by cable AB as shown. The tension in cable AB (T

_{AB}) acting at point B creates a moment about point O (M

_{O}) equal to -900i+M

_{y}j-315k lb-ft, where M

_{y}is unknown.

a) What is the length of the pole (L

_{BC})?

b) What is the magnitude of the tension, T

_{AB}?

## Homework Equations

M

_{O}=π

_{AB}xF

**T**

_{AB}=u

_{AB}|T

_{AB}|

## The Attempt at a Solution

Vector BO <0,-(h+1),6>

Vector BA <4,-h,-6>

|BA|= [itex]\sqrt{h^{2}+52}[/itex]

**T**

_{BA}= T

_{BA}[itex]\frac{<4,-h,-6>}{|BA|}[/itex]

I cross multiplied and got T

_{BA}<[itex]\frac{12h+6}{|BA|}[/itex],[itex]\frac{24}{|BA|}[/itex],[itex]\frac{4h+4}{|BA|}[/itex]>

In order to solve for the height of the pole, I need T

_{BA}. Where i get stuck is here, and a lack of confidence that my vectors BA and BO are correct. In order to solve for the height of the pole, I need the tension, but that is the second part of the problem.

EDIT: tips on how to fix the itex tags would be appreciated,too.

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