# Homework Help: 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:

• ###### 10.JPG
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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)