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# Trigonometry Problem - 50 Frih\$

melissareich

Solve and get 50 Frih\$
Round to the nearest tenth!
sin 115 / x = sin 40 / 3
x = 4.23

By tenth is that 1/10.
if you I have rounded wrong x = 4.229893856
melissareich
Corrrrect!

x = 4.2
^what I meant by tenth
oh.. I rounded wrong because I thought wrong but the important thing is that the answer was correct.

Thanks for the 50 Frih\$!
imagefree
 Peterssidan wrote: sin 115 / x = sin 40 / 3 x = 4.23 By tenth is that 1/10. if you I have rounded wrong x = 4.229893856

well i am a littlebit confuse here (i am not good at trignometry), can you please tell me how is this solution?

I personally feel the answer should be 4.7
Gushe
Me too..
Well, it might be stupid, but can't you use Cosinus and Sinus etc only in triangles with 1 ninety degree corner..? that's wa we learnt I think..
(srry for my bad english )
It's the Law of sines.
dac_nip
very simple dude. Its the LAW of SINES.. hayy. it was already answered..
melissareich
Yes it was the Law of Sines, this particular triangle is AngleSideSide.

You initially had to draw 2 different triangles, there could have been 2 different answers, but the second triangle equalled more than 180.

 Gushe wrote: Me too.. Well, it might be stupid, but can't you use Cosinus and Sinus etc only in triangles with 1 ninety degree corner..? that's wa we learnt I think.. (srry for my bad english )

You cannot use Law of Cosines because these are not right triangles, they are Oblique triangles.
Gushe
Well.. I'm only 14 years old And I'm in fourth grade (It's appareantly different than in US etc..) and we didn't learn it yet.. though I could have tried

~Gushe
rvec
you could've solved it one sec i'll show how.

sin115=BD/3
BD=sin115*3
sin40=BD/x
x=BD/sin40=3,8

eeeh maybe not
edit:
lol my calculator still did radials
sin115=BD/3
BD=sin115*3
sin40=BD/x
x=BD/sin40=4,2
mtorregiani
Quite easy.
May I suggest a new one?

Find the angle X

Winner gets 50 frih\$

PS: I love Trigonometry!
If sen is the same as sinus

1 - (cos x)^2 - cos x - 1 = 0
(cos x)^2 + cos x = 0
x = pi

or if you want it in degrees: x = 180
mtorregiani
Great

Yes, sen is sinus.