Vectors and trig functions.

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Promilla

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The sum of three nonzero vectors: OA, OB and OC is equal 0. Angle between vector OB and OC is α, between OC and OA - β, between OA and OB γ. Then OA:OB:OC is equal? ( it has to be expressed with trigonometric functions)
Maybe some hints?
 
Promilla said:
The sum of three nonzero vectors: OA, OB and OC is equal 0. Angle between vector OB and OC is α, between OC and OA - β, between OA and OB γ. Then OA:OB:OC is equal? ( it has to be expressed with trigonometric functions)
Maybe some hints?
Click to expand...

Think about polygon of vectors in equilibrium and law of sines.

Please share your work with us, indicating exactly where you are stuck - so that we may know where to begin to help you.
 
Sorry.
So I've drawn these vectors and I was trying to find a link between angles and trig function.
But I don't know what next . I can't express this relation because these are not right angles. But I will try use your hint.
 
I've drawn a triangle from these three vectors and I was trying to find the relation between angles and sides of this triangle. But as I said. I'm not sure how to do this because I have not such exercise in school. I'm sorry. I'm really trying to do this.
 
Promilla said:
I've drawn a triangle from these three vectors - Correct first step

and I was trying to find the relation between angles and sides of this triangle. But as I said. I'm not sure how to do this because I have not such exercise in school. I'm sorry. I'm really trying to do this.
Click to expand...

But how did you arrive at your solution (cosα: cosβ:cosγ)?

Did you read my hint carefully?
 
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Ok . so I haven't seen this one about Law of sines. But I don't know which angles from α, β,γ represent which angle in my triangle. :(
 
Can someone PM the answer to me? It's not my homework or anything, I just want to re familiarize myself with vectors and I don't understand this.
 
Promilla said:
Ok . so I haven't seen this one about Law of sines. But I don't know which angles from α, β,γ represent which angle in my triangle. :(
Click to expand...

Didn't your first post say that angle alpha was formed by OB and OC, beta was formed by OC and OA and gamma is OA and OB?

Or is the vector not the triangle?
 
Yes. but when we are adding vectors (according to law of polygon of vectors) it's not the same, as far as I understand.[h=1][/h]
​
 
Ok . I've tried to use Law of sines and I have that the answer is : sinα: sinβ:sinγ. I hope this time it is right ?
 
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