Anyone here good at math?

[snakeguy101]

I need help with the following trig problem and my tutor is out of town and out of touch...

A boat leaves a port and travels due east. From the port, there is an island 45.2 miles away on a bearing of 65.0º. After a boat has traveled 31.2 miles, find the bearing angle of the island from the boat. All bearing angles measures clockwise from due north.

here is what I have so far:
using the law of cosines, a^2=45.2^2 + 31.2^2- 2(45.2*31.2)cos(25), a=21.45
Then using the law of sines, I get (sinB/45.2)=(sin25/21.45)
SinB=.89055... Sin(^-1)(.89055)=B=62.9º

but B≠62.9º since it must be an obtuse angle in order to fit this application.

A=25º, a=21.45mi
B= 62.9º? b=45.2mi
C=92.1? c=31.2mi

Thanks in advance for your help. I know this is not really the place to look but I figured it is worth a shot.

 

[Juxtaroberto]

Oops, nevermind if you read what I wrote. I misread distance as degrees.

I totally forgot everything about trig.

 

[Juxtaroberto]

Oops, I almost forgot. You can get awesome help with this kind of stuff at physicsforums.com. I know they're a physics forums, but they've got a bunch of other stuff, including trig.

 

[snakeguy101]

Thanks, I will look into it.

 

[packer43064]

I hate math.

 

[Mudslinger14]

2....Thats the answer...2...

 

[snakeguy101]

I figured it out! I was getting a reference angle of 69.2º. I just needed to add 90º to it to get the correct angle in the triangle or subtract 69.2º from 90 to get the proper bearing angle from due north!

Answer=27.1º....I hope....

freakin took me 4 hours to figure that out and guess where I learned it! Youtube. who knew?

 

[packer43064]

4 hours!!!! I would have honestly skipped it and lost some points. I'm not wasting 4 hours on that, get a 75% on the homework assisgnment and go on with life. This is probably why I'm not good in my math classes, lol.

 

[snakeguy101]

HOnestly I would have skipped it but this is a take home test that will replace our lowest test grade so I am shooting for a 100% so that I can boost my GPA and in turn the amount of money I will be getting from scholarships...I am currently hanging in space between a B and a C in this class but if I get an A on this and anything higher than an 80% on the final, I will have an A for the semester.

 

[packer43064]

Good reason.