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Mathematics 15 Online
OpenStudy (cutiecomittee123):

Law of sines question!

OpenStudy (cutiecomittee123):

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OpenStudy (cutiecomittee123):

What is the value of x?

zepdrix (zepdrix):

Remember your law of sines? :) \(\large\rm \frac{\sin(A)}{a}=\frac{\sin(B)}{b}\) Where side a is opposite angle A, and same for the b's.

zepdrix (zepdrix):

So um... which angle is opposite the side length labeled 14? :)

OpenStudy (cutiecomittee123):

yes, which one is angle a,b, and c in this case though?

OpenStudy (cutiecomittee123):

14 and 45 match and x and 60 match

zepdrix (zepdrix):

|dw:1451876083777:dw|Good good good :) So thats the information we'll want to use.

OpenStudy (cutiecomittee123):

is 14 A?

zepdrix (zepdrix):

I was calling the angles the capital letters, so I guess A=45, a=14, ya? ^^

OpenStudy (cutiecomittee123):

yes, makes sense

zepdrix (zepdrix):

Do you think you can plug in the pieces of information correctly? Get this kind of setup? :)\[\large\rm \frac{\sin(A)}{a}=\frac{\sin(B)}{b}\]

OpenStudy (cutiecomittee123):

14/45=x/60

zepdrix (zepdrix):

Oh boy, you didn't use your sine function at all XD

OpenStudy (cutiecomittee123):

sin14/sin45=sinx/sin60

zepdrix (zepdrix):

Oh you :P lol

OpenStudy (cutiecomittee123):

the sine dosnt go before the denominator does it?

zepdrix (zepdrix):

Correct, we apply sine to `angles`.

OpenStudy (cutiecomittee123):

numerator*

zepdrix (zepdrix):

The denominator is a side length :) No sine for him.

OpenStudy (cutiecomittee123):

okay

OpenStudy (cutiecomittee123):

wait so then shouldnt it be 45sin/15 and 60sin/x

zepdrix (zepdrix):

Mmm ok looks good besides that small typo you made :)\[\large\rm \frac{\sin(45)}{14}=\frac{\sin(60)}{x}\]Now we solve for x. Just a few little algebra tricks.

zepdrix (zepdrix):

oh I misrea what you wrote lol XD

zepdrix (zepdrix):

darn I spilled the beans :d

zepdrix (zepdrix):

When we take this proportion, the `sine of an angle` to the `side opposite that angle`, Law of Sines is telling us that this proportion is always the same regardless of which side/angle pair we choose.

OpenStudy (cutiecomittee123):

yes

zepdrix (zepdrix):

Anyway, we take the sine of the angles, the angles are 45 and 60 degrees in this case. sin(45)/14 = sin(60)/x Hopefully that's not too confusing D:

OpenStudy (cutiecomittee123):

so what we already did was right

zepdrix (zepdrix):

Yes, we're here currently :)\[\large\rm \frac{\sin(45)}{14}=\frac{\sin(60)}{x}\]Have you learned about your "special angles" yet? sin(45) and sin(60) work out to nice values that we don't need a calculator for.

OpenStudy (cutiecomittee123):

Hmm I may have but i need a refresher

zepdrix (zepdrix):

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