How do I find Vector C in a non-right triangle using the Law of Cosines?

In summary, the conversation focused on finding the length of side C in a triangle using vector components. The law of cosines was suggested as a potential method for solving the problem.
  • #1
stolencookie

Homework Statement


Vector A: 1.96N at 20° Vector B: 1.71N at 65°
There are different parts I did the graph part by hand. I am having trouble finding it analytically. We have to use cm for our triangle.

Homework Equations

The Attempt at a Solution


Vector A: 1.96 cm at 20°
Vector B: 1.71 cm at 65°
Vector C: ? at 95°
180°-85°=95°
Then I had trouble after that since it isn't a right triangle. Would I use sine laws or cosine laws? I am lost.
 
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  • #2
If I understand the problem correctly, side ## A ## makes an angle of 20 degrees with side ## C ##, and the angle opposite side ## C ## is angle ## c= 65 ## degrees. If that is correct, the law of cosines can be used to find side ## C ##: ## \\ ## ## C^2=A^2+B^2-2AB \cos(c) ##. ## \\ ## It would help to have a diagram, but I think I got it right.
 
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  • #3
Charles Link said:
If I understand the problem correctly, side ## A ## makes an angle of 20 degrees with side ## C ##, and the angle opposite side ## C ## is angle ## c= 65 ## degrees. If that is correct, the law of cosines can be used to find side ## C ##: ## \\ ## ## C^2=A^2+B^2-2AB \cos(c) ##. ## \\ ## It would help to have a diagram, but I think I got it right.

Thank you, I wish i knew how to put up a triangle...
 
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FAQ: How do I find Vector C in a non-right triangle using the Law of Cosines?

What are vector triangles?

Vector triangles are a visual representation of the forces acting on an object. They use arrows to indicate the direction and magnitude of the forces, and can be used to determine the resulting net force on the object.

How do you draw a vector triangle?

To draw a vector triangle, first determine the forces acting on the object and their respective directions and magnitudes. Then, draw the forces as arrows on a diagram, making sure to properly label them. Finally, draw the resultant vector by connecting the tail of the first force to the head of the last force.

What is the purpose of a vector triangle?

The purpose of a vector triangle is to determine the net force acting on an object. By using vector addition, we can find the resultant force and determine if the object will accelerate, decelerate, or remain at a constant speed.

What happens if the vector triangle closes?

If the vector triangle closes, it means that the forces are balanced and there is no net force acting on the object. This can happen in two ways: when the forces are equal and opposite, or when the forces are arranged in a way that they cancel each other out.

How can I use a vector triangle to solve problems?

You can use a vector triangle to solve problems by breaking down the forces into their x and y components, and then using trigonometry to find the resultant force. This allows you to determine the direction and magnitude of the net force acting on the object.

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