need help im going to draw a triangle and im doing the law of sines so if anyone can help please do cuz im confused.. please click this to helpp

- anonymous

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- anonymous

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- anonymous

Do you need to find a?

- anonymous

so let me explain im trying to find a okay c=96.3, b=145.67 , B=39.5degrees, C=74.2degrees,

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## More answers

- anonymous

law of sines is a/sinA=b/sinB

- anonymous

Sine rule says:
SinA/a = SinB/b = SinC/c

- anonymous

okay i understand that
waitt why is it sina/a instead of a/sin a

- anonymous

SinA/a = Sin(39.5)/145.67
SinA = a*something

- anonymous

Because they mean the same thing. A/B = C/D => B/A = D/C

- anonymous

waitt does it even matter

- anonymous

okay im not understanding

- anonymous

You can find angle A by simply subtracting angles B and C from 180.

- anonymous

okay i understand which would be 66.8

- anonymous

Then, use this:
SinA/a = Sin(39.5)/145.67
SinA = a*something
SinA/something = a
To find a.

- anonymous

SinA/a = SinB/b = SinC/c
IS SAME AS
a/SinA = b/SinB = c/SinC

- anonymous

but then a would be .00436

- anonymous

I am getting 210.5

- anonymous

That "something" in my expression is 0.00436. Divide Sin66.8 by that "something" value. Then, you get the value of a.

- anonymous

really then let me try again...... im still not getting that are you multiplying or dividing

- anonymous

SinA/a = Sin(39.5)/145.67
SinA = a*0.00436
a = SinA/0.00436
a = Sin66.8/0.00436
a = 210.5

- anonymous

im not getting it first you divided than you did something else im so confused

- anonymous

ok

- anonymous

i also had another question

- anonymous

Post it separately.

- anonymous

i dont understand

- anonymous

Which part don't you understand? :) I can help you.

- anonymous

okay, so instead of 66.8 its 66.3

- anonymous

im so fustrated im confusedd

- anonymous

Punch it into the calculator and you get slightly different number from 210.5

- anonymous

SinA/a = Sin(39.5)/145.67
SinA = a*0.00436
a = SinA/0.00436
a = Sin66.3/0.00436
a = 210

- anonymous

i neeed helpppp

- anonymous

i got -47.99

- anonymous

Check your calculator first. I'm guessing you're getting different answers because your calculator is not in degree mode. That's why it's treating your angles differently.

- anonymous

wait no i got -110.05

- anonymous

How in the world can a length of a side of a triangle be negative? Can you show the arithmetic you used to get that number?

- anonymous

yeppp m ycalculator wasnt in degree mode so let me try again

- anonymous

yayy i got 209.69

- anonymous

Good....close enough to 210. :)

- anonymous

next problem
b=58.2
c=68.3
C=51.3 degrees
were gunna find a

- anonymous

At this point, it is simply plugging in values into that sine rule ratios and cranking out numbers in a calculator. There is not much help you need.

- anonymous

yeaa but i want to do it my self then have someone do it so i can nn check my answer to make sure its correct

- anonymous

i got 7105. 88

- anonymous

is my answer correct thats all im asking

- anonymous

It can't be that big.

- anonymous

Angles are almost close to each other. So, side lengths have to be close to each other too.

- anonymous

well i must be doing something wrong but sin68.3/51.3=.018111746

- anonymous

128.7/.018111746=7105.88

- anonymous

b=58.2 c=68.3 C=51.3 degrees
SinB/b = SinC/c => SinB = 58.2 * Sin(51.3)/68.3 => SinB = 0.665
B = 41.68

- anonymous

becuase i couldnt find A or B so i figured they were the same
by suntracting 180-51.3

- anonymous

ohhh ok so u must follow the formula

- anonymous

Now that you know B, you find A by doing 180 - 51.3 - 41.68 = 87

- anonymous

noww i get it

- anonymous

SinA/a = SinC/c
=> a = c * SinA/SinC
=> a = 68.3 * Sin(87)/Sin(51.3)
=> a = 87.4

- anonymous

ok

- anonymous

@dessyk
The following variations of Law of Sines are the same:
\[\frac{a}{\sin(A)} = \frac{b}{\sin(B)}=\frac{c}{\sin(C)}\]
and
\[\frac{\sin(A)}{a}=\frac{\sin(B)}{b}=\frac{\sin(C)}{c}\]

- anonymous

He got that. :)

- anonymous

ok :)

- anonymous

hello

- anonymous

yeah

- anonymous

i have another question but hoew did you get 41. sometrhing but i got 45.42

- anonymous

You mean for B = 41? I did the inverse sine function on the value 0.665.

- anonymous

yes, ohh reallyy you see im confused now i thought u just i thought u just took .6650*68.3=45.42

- anonymous

Sin(B) = 0.665
=> B = inverse sine (0.665). On the calculator, you have to first press 0.665. Then, inv button, then the sin button.

- anonymous

That gives you angle B.

- anonymous

i didnt get that

- anonymous

dessyk.. nice drawing.. :) :)

- anonymous

thank you i guesss lol can yoiu help me!!

- anonymous

what is the question

- anonymous

its up above next problem
b=58.2
c=68.3
C=51.3 degrees
were gunna find a

- anonymous

law of sines

- anonymous

i didn't see above but u can find it very easily..
the formula is
sin a / a = sin b / b = sin c / c
or
a /sin a = b / sin b = c / sin c
use any of them what caters ur problem

- anonymous

okay but when i tried i started to get fustrated because i wasnt getting the righ tanswer

- anonymous

did my answer help u even a bit or not ?

- anonymous

a little bit its just that i need help going through the process

- anonymous

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- anonymous

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- anonymous

get it?

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