Find angles between two rope and the ceiling

1. Sep 20, 2011

seanster1324

***Excuse the pluralization error in the title***

1. The problem statement, all variables and given/known data

I attached a picture below...

2. Relevant equations

sin^2(theta)+cos^2(theta)=1

a^2+b^2=c^2

Vector properties

Trig identities

3. The attempt at a solution

I am familiar with trig identities and vector properties, but I can't get anywhere with this. I tried using the 697N weight as the y-component vector for either side, but that didn't work.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Attached Files:

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2. Sep 20, 2011

PeterO

resolve each tension into vertical and horizontal components.
The horizontal components have to balance each other,
The vertical components together support the mass.

3. Sep 20, 2011

seanster1324

I understand that part. The part I don't understand is how to separate each vector into its components. I only have the magnitude with no given angles. Looking at the hint, I need to play around with some trig. But I can't see how to incorporate the identity it hints at.

And I can't use 697N as the shared vertical component, right? Because that would make this much easier, but it did not work for me.

Last edited: Sep 20, 2011
4. Sep 20, 2011

PeterO

You have two unknowns, theta 1 and theta 2

Vertical considerations will give one equation involving them

Horizontal considerations will give a second equation connecting them

Two equations in two unknowns should mean a simultaneous equations solution is possible.

EDIT: you could also use the cosine rule to find the angles.

Last edited: Sep 20, 2011
5. Sep 20, 2011

seanster1324

Ah, I see what you mean. Thank you so much!

6. Sep 20, 2011

PeterO

Note my edit about the cosine rule.

7. Sep 20, 2011

seanster1324

Witch cosine rule? The Law of Cosines?

8. Sep 20, 2011

PeterO

yes: a2 = b2 + c2 - 2bc.cos(A)