June 14th, 2010, 07:24 PM  #1  
Member Joined: Jun 2010 From: USA, Texas Posts: 85 Thanks: 0  Sine/Cosine Triangle
Question: Quote:
 
June 14th, 2010, 08:31 PM  #2  
Global Moderator Joined: Nov 2009 From: Northwest Arkansas Posts: 2,766 Thanks: 4  Re: Sine/Cosine Triangle Quote:
A car travels in a direction at a given speed, for a certain amount of time. 55mph * .25hours is the distance this car has traveled, so draw a ray on a piece of paper and declare its length to be 55*.25 miles. Now draw another ray from the same point so that the two rays make an angle of (about) 70 degrees. /_ Those two characters (the / and the _ ) intersect at an angle close enough to 70, IMO. This second ray has length 30*.25 label it. Label the angle between the rays 70degrees. Use the law of cosines to find the distance between the endpoints of the rays (crap, I should have used "vector" instead of "Ray"... Too hard to edit it from my phone, so maybe a benevolent joker will help me out!) so yeah. Law of cosines.  
June 14th, 2010, 09:09 PM  #3 
Member Joined: Jun 2010 From: USA, Texas Posts: 85 Thanks: 0  Re: Sine/Cosine Triangle
Oh I see, so SAS is my route to go? Thanks :] 
June 15th, 2010, 06:37 AM  #4 
Global Moderator Joined: Nov 2009 From: Northwest Arkansas Posts: 2,766 Thanks: 4  Re: Sine/Cosine Triangle
When you know the values of SAS or SSS, use law of cosines. When you know mostly angles, use law of sines.

June 15th, 2010, 07:22 AM  #5 
Global Moderator Joined: Dec 2006 Posts: 20,931 Thanks: 2205 
What were the choices for the answer?

June 15th, 2010, 11:27 AM  #6 
Member Joined: Jun 2010 From: USA, Texas Posts: 85 Thanks: 0  Re: Sine/Cosine Triangle
a. 15.9 miles b. 11.2 miles c. No correct answer d. 12.6 miles e. 13.2 miles (ANSWER) 
June 15th, 2010, 11:44 AM  #7 
Global Moderator Joined: Dec 2006 Posts: 20,931 Thanks: 2205 
I'd prefer answer (c), as the question tells you that the cars leave the intersection, but doesn't say that they don't both use the same road.

June 15th, 2010, 11:56 AM  #8  
Global Moderator Joined: Nov 2009 From: Northwest Arkansas Posts: 2,766 Thanks: 4  Re: Quote:
 
June 15th, 2010, 12:36 PM  #9 
Global Moderator Joined: Dec 2006 Posts: 20,931 Thanks: 2205 
If there are two possibilities, choice (e) isn't the correct answer, just a possibility.


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sine or cosine, triangle 
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