Trigonometry Law of Sines topscore. help?

[taffy]

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Hi,

Requesting help for trig/law of sines/topscore question. I have attached screenshot.

Will someone please explain how to determine that sinB = 1/4 from what was given?

Thank you so much!

 

[Lnguyen7]

Law of sine:
sinA/a = sinB/b = sinC/c
Rearrange
sinB = b*sinA/a = 3*(1/2)/6 = 1/4

 

[alexis2010]

Was sinB given??
Is the question asking to compare sinA to 1/2.?
Law of sines: sinA/6 = sinB/3
Cross multiply and divide and you get:
SinA = 2 sinB. This is as far as you can go.
Can you post the complete question?

 

[taffy]

I guess I don't understand how the quantity A/B is defined. I understood it as if the only information that was given was a=6, b = 3, and some quantity B= 1/2 for comparison.

Lnguyen7, how do you know that sinA = 1/2? I didn't think it was given?

Here is a screen shot of the entire question and my scratch work. Thank you for the input!

 

[alexis2010]

your work is correct. My question is where does 1/4 come from????
this is a typical GRE question. for the DAT you don't have to compare 2 quantities
my answer to this question is D

 

[taffy]

Is it possibly a typo?

So, I just want to confirm what you typed is that these type of comparing 2 quantities questions are not on the DAT? There are a lot of these in the topscore practice tests.

Thank again =-)

 

[alexis2010]

No they are not. These are typical GRE questions. My brother is studying for the GRE and I'm helping him with the quantitative reasoning.
That's how I know. For the DAT you are given 5 choices and you have to pick the right answer.
If you have any questions I'l be glad to help

 

[Lnguyen7]

I guess I don't understand how the quantity A/B is defined. I understood it as if the only information that was given was a=6, b = 3, and some quantity B= 1/2 for comparison.

Lnguyen7, how do you know that sinA = 1/2? I didn't think it was given?

Here is a screen shot of the entire question and my scratch work. Thank you for the input!

View attachment 193424 View attachment 193425

Now that you posted the choice, what I did doesn't make any sense. I thought sinA was given as 1/2 and you wanted to find sinB.
I am with you on this. I am not sure how they got sinB = 1/4.
Is this a right triangle? A looks like 90degree to me.

 

[taffy]

I don't think it is a right triangle. If it was then sinA = opp/hyp = 6/3 , but 6 looks like a hyp. Anyway, that little square isn't in the triangle to indicate right, so I guessed it wasn't.

The correct answer is supposed to be that the two quantities are equal.

It would make sense if sinB = 1/4 was given. I'm thinking it was omitted by mistake. I'll try emailing topscore the question to find out.