A dog runs 2.5m east and 6.0m north. What are the magnitude and direction of the dog's displacement with respect to its original position?
* I know I need to use SOHCAHTOA but unsure of which part of it and how to enter on calcuator (TI-83 Plus).

Question

noelgreco · Answer

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Are you going to use SOH CAH or TOA to find the angle at O ?

anonymous · Answer

TOA- but how do you get the angle measurement? I am not getting any of my answer choices. Maybe I am doing sometime wrong on my calculator, but I am doing tan^-1(6/2.5). How do you calculate?

anonymous · Answer

*something

anonymous · Answer

Hello there, uhm, the diagram by NoelGreco is just perfect. You can label the 2.5m A and the 6m line B. You need to find the x and y components of the resultant R.

anonymous · Answer

$$Rx= Ax+Bx, Ry = Ay +By $$ That way you have 2.5 +0, and 0+6

noelgreco · Answer

You're making the correct entry.  Make sure your MODE is degrees on the 83.. What kind of answer are you getting when you enter what you do?

anonymous · Answer

Rx=2.5, Ry=6.0. R will therefore be equal to $$\sqrt{(2.5)^2+(6)^2}$$

anonymous · Answer

When I do inverse tan (6/2.5) I get 1.176 
This is not an answer choice :/

anonymous · Answer

fall2012- thank you- what you gave me is the pythagorean theorem, right? and it gets me the resultant displacement?

anonymous · Answer

the arctan of(6/2.5) on my calculator is 67.38

noelgreco · Answer

That's because the andle mode of the 83 is set to radians.  Your answer is correct in radians.  You need to change the mode if you want degrees (it's 67.38, by the way)

anonymous · Answer

yeah

anonymous · Answer

Do you know how to set to degrees?

noelgreco · Answer

Yes.  I have a 300 page TI-83 manual.  Looking now.

anonymous · Answer

Thanks so much!

anonymous · Answer

need to get one of those... mine is used and didn't come with one.

noelgreco · Answer

Press the MODE button.  It's in the top row of the main keyboard

anonymous · Answer

Ok, I see. I just selected Degree. MERCI :) This is what I needed!

noelgreco · Answer

OK.  So you got the angle , and then the displacement is simply found with Pythagoras.

anonymous · Answer

Yes. What I am getting now matches up with an answer choice and I understand why.

noelgreco · Answer

Tres bon.