Two hanging masses and three strings

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Lennie
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Homework Statement


Two masses m and M (where M = 2m) are attached with strings. One mass m is suspended from a single vertical string held by two strings each at 45 degrees to the horizontal. The suspending string to the left at 45 degrees is attached to a fixed point. The string on the right at 45 degrees is attached to another mass M which in turn is attached by a further to a fixed point above at an angle theta to the horizontal.
If the system is in equilibrium, determine the tension in the three strings in terms of m and g, and calculate the angle theta.[/B]

Homework Equations


F = ma

The Attempt at a Solution


As the system is in equilibrium i can say a=0 and therefore ΣF = 0.
The y component of the two tensions in the two diagonal strings supporting mass m should be equal to mg when summed. Assuming the tensions are still equal (not quite sure what effect the other mass M would have on this - mass M is what has thrown me) then the tension in the bottom two strings should be mg/√2 ?
The tension in the 3rd string connecting mass M with the fixed point ? My best quest was to say it is equal to √2mg as 2mg sin45 = T ?
I also don't know theta however and don't see a way of finding it, at this point I am almost sure i have absolutely none of this right! Any help on a method to solve this would be much appreciated!

P.s sorry for the lack of image, can't seem to find anything on the web which shows a similar situation.
 
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Lennie said:
As the system is in equilibrium i can say a=0 and therefore ΣF = 0.
Good.

Lennie said:
The y component of the two tensions in the two diagonal strings supporting mass m should be equal to mg when summed.
Good.

Lennie said:
Assuming the tensions are still equal
No need to assume that... prove it!

Lennie said:
The tension in the 3rd string connecting mass M with the fixed point ? My best quest was to say it is equal to √2mg as 2mg sin45 = T ?
Why guess? Apply ΣF = 0 to mass M and solve for the unknowns.

Lennie said:
P.s sorry for the lack of image, can't seem to find anything on the web which shows a similar situation.
You can use the whiteboard to slap something together yourself.