Trigonometry or components to find the displacement

In summary, the conversation discusses a problem where Bob walks and jogs in different directions, and the goal is to find the displacement that will return him to his starting point by the most direct route. The solution involves using trigonometry to find the components of each vector and then using the Pythagorean theorem to calculate the displacement. The confusion arose from not correctly identifying the components of each vector, but it was resolved by imagining each vector as a right angled triangle and using the correct angles.
  • #1
ScullyX51
36
0
1. Homework Statement :
Bob walks 360 m south, then jogs 490 m southwest, then walks 360 m in a direction 35 degrees east of north.
Use either trigonometry or components to find the displacement that will return Bob to his starting point by the most direct route. Give your answer as a distance.
Express your answer using two significant figures.


3. The Attempt at a Solution :
I drew a diagram and got the components of each.
360(cos35)(sin35)
490(cos35)(sin35)

For the components I got:
(0,360)
(401.38,281.05)
(294.89,206.49)
Then I added the x's and y's and used pythagoreum theorem, and I got d=1096.87, which isn't correct. What am I doing wrong??
 
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  • #2
y components = -360m + -490cos(45) + 360cos(35)
x components = 0 + -490sin(45) + 360sin(35)

Then use pythagoras.
Make sure you get positives and negatives correct depending on which way he's travelling.

Why did you do 360(cos35)(sin35) ? and 490(cos35)(sin35) ?
You need to imagine each trajectory as a right angled triangle with the two short sides along the North/South and East/West planes and the hypotenuse being his travel path.
You know all of the angles ie. 35 degrees and SouthWest = 45 degrees west of south.
 
  • #3
Thank you that worked! I was confused about what to use for the components of each vector. I did that because I thought to get the components I would multiply the length times the x and y components of each. (the sin and cosine). I don't know, I am really lost with this chapter.
 

Related to Trigonometry or components to find the displacement

1. What is trigonometry and how is it used to find displacement?

Trigonometry is a branch of mathematics that deals with the relationships and properties of triangles. It is used to find displacement by using the principles of sine, cosine, and tangent functions to calculate the missing side lengths or angles of a triangle. This information can then be used to determine the displacement of an object or point in space.

2. What are the components needed to find displacement using trigonometry?

To find displacement using trigonometry, you will need the length of at least one side and one angle of a triangle. This can be achieved by measuring or knowing the initial and final positions of an object, as well as the angle of its displacement. In some cases, you may also need the length of a second side or angle to accurately calculate the displacement.

3. Can trigonometry be used to find displacement in three-dimensional space?

Yes, trigonometry can be used to find displacement in three-dimensional space. In this case, you will need to use the principles of three-dimensional trigonometry, which involves using different trigonometric functions and formulas to calculate the missing side lengths or angles in a three-dimensional triangle.

4. How does the Law of Cosines help in finding displacement using trigonometry?

The Law of Cosines is a trigonometric formula that relates the sides and angles of a triangle. It is particularly useful in finding displacement as it can be used to calculate the missing side length when two sides and an angle are known. This information can then be used to determine the displacement of an object or point in space.

5. Can trigonometry be used to find displacement in non-right triangles?

Yes, trigonometry can be used to find displacement in non-right triangles. In these cases, you will need to use the principles of the Law of Sines, which relates the ratios of the side lengths and angles of a non-right triangle. This can be used to find the missing side lengths or angles, which can then be used to calculate the displacement of an object or point in space.

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