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April 17th, 2013, 03:58 AM   #1
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Cosine and Sine laws

Some help here please. Don't get these four questions.
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April 17th, 2013, 04:54 AM   #2
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Re: Cosine and Sine laws

For the first one you need to use the cosine law. There is a simple explanation here http://www.mathsisfun.com/algebra/trig-cosine-law.html

So we can write:





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April 17th, 2013, 05:04 AM   #3
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Re: Cosine and Sine laws

For the second one you need to rearrange the cosine law.



Plugging in the values:





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April 17th, 2013, 05:14 AM   #4
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Re: Cosine and Sine laws

The third one you need to use the sine law for:



We know that all the internal angles of a triangle add up to 180 degrees so:



We know the length AC and the angle opposite it and we know the angle opposite the side we wish to calculate.



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April 17th, 2013, 05:15 AM   #5
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Re: Cosine and Sine laws

The fourth one is very similar to the third one.
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April 17th, 2013, 06:25 AM   #6
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Re: Cosine and Sine laws

Thank you SO MUCH !!!


thank you, again !


Question resolved. ~
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