Pre-Calc Help

Montanasvt · February 26th, 2009, 04:43 PM

here's the problem if you're up for it... any help is greatly appreciated...

A fisherman leaves his home port and heads in the direction N 70* W. He travels 30 miles and reaches Egg Island. The next day he sails N 10* E for 50 miles., reaching Forest Island. Find the distance between the fishermans's home port and Forrest Islan. Find the bearing from Forrest Island back to his home port.

Thanks

AnimalCrackers · February 26th, 2009, 05:32 PM

I'm unfamiliar with the manner you're describing his directions. Clarify if you mean 70 degrees West of North, or 70 degrees North of West. ditto for the N-E direction. This should just be simple vectors though. you've got a triangle of 30 miles and 50 miles, so the hypotenuse is SQRT(30^2+50^2) = 58.31 miles. Once you figure out the angle, you're done.

Whiskey11 · February 26th, 2009, 05:44 PM

Originally Posted by AnimalCrackers

I'm unfamiliar with the manner you're describing his directions. Clarify if you mean 70 degrees West of North, or 70 degrees North of West. ditto for the N-E direction. This should just be simple vectors though. you've got a triangle of 30 miles and 50 miles, so the hypotenuse is SQRT(30^2+50^2) = 58.31 miles. Once you figure out the angle, you're done.

Win...

I remember pre calc, my teacher was an idiot and I got an A because no one else knew (not even the teacher) what the hell was going on. It was great.

AC got it. The angle is a simple inverse tangent function. Make sure to keep the reference correct!

zinc02GT · February 26th, 2009, 05:59 PM

Originally Posted by AnimalCrackers

I'm unfamiliar with the manner you're describing his directions. Clarify if you mean 70 degrees West of North, or 70 degrees North of West. ditto for the N-E direction. This should just be simple vectors though. you've got a triangle of 30 miles and 50 miles, so the hypotenuse is SQRT(30^2+50^2) = 58.31 miles. Once you figure out the angle, you're done.

Not sure on your numbers, but yes that is how you work it.

That is more of a geomety problem if you ask me.

yojoe600 · February 26th, 2009, 06:00 PM

im in college calculus and i have no idea... i did jsut fail my test today though

zinc02GT · February 26th, 2009, 06:04 PM

It's just a triangle.

If you look ati in your head with images, think of a starting point and you go to X at so many degrees, Then you turn (for example sake) right at so many degrees. Based upon those to point that you have reached with those degrees, whatis the remaining side.

That's what it seemed like to me

mooses · February 26th, 2009, 06:31 PM

Keep in mind that you cannot use the pythagorean theorem unless it is a right triangle.

Whiskey11 · February 26th, 2009, 06:34 PM

Originally Posted by mooses

Keep in mind that you cannot use the pythagorean theorem unless it is a right triangle.

Correct but you can use a series of right triangles (using the known lengths as the hypotenuses) to figure everything else out. We did this in our Algebra based physics class in Highschool and I remember it very well.

Too bad I cant explain it for poo though.

mooses · February 26th, 2009, 06:43 PM

Assuming you mean 70* west of north and 10* east of north, I got 48.723 miles at 25.35* east of south.

I used law of cosines to get the hypotenuse and the angles... I'd double check my math as I pictured most of it in my head and it could be wrong.

edit: actually this is incorrect, I assumed the distance was the hypotenuse of the triangle. I used it as the C in the law of cosines, and since it is not the hypotenuse, it isn't right. Just use an inverse tan like Atlantic Blue said, it'll give you the angle and then you can solve for the length and other angles easily.

Safi · February 26th, 2009, 06:46 PM

Originally Posted by Whiskey11

Correct but you can use a series of right triangles (using the known lengths as the hypotenuses) to figure everything else out. We did this in our Algebra based physics class in Highschool and I remember it very well.

Too bad I cant explain it for poo though.

Using a series of right triangles is just a waste of time...This is how it should be done, right triangle = use pythagorean theorem, and all other trianges use sin/cos/tan

AtlanticBlue99 · February 26th, 2009, 06:47 PM

It is an inverse tangent function.

AnimalCrackers · February 26th, 2009, 07:00 PM

Originally Posted by mooses

Assuming you mean 70* west of north and 10* east of north, I got 48.723 miles at 25.35* east of south.

I used law of cosines to get the hypoteneuse and the angles... I'd double check my math as I pictured most of it in my head and it could be wrong.

yap, what he said

I always sucked at Geometry

Montanasvt · February 26th, 2009, 09:42 PM

Well I got the answer... its not geometry... and its not a right angle... you can only solve right angles using A^2+B^2.... i had to use Law of Cosines and Sines...thanks for all the input guys...

the answers where... Distance: 63 miles Bearing : S 162* E

February 26th, 2009, 04:43 PM	#1
Montanasvt Regular 03 10th Ani Cobra Vert 12.20@115 Join Date: Oct 2007 Location: Macon, Ga Posts: 409 iTrader: 0 reviews	Pre-Calc Help here's the problem if you're up for it... any help is greatly appreciated... A fisherman leaves his home port and heads in the direction N 70* W. He travels 30 miles and reaches Egg Island. The next day he sails N 10* E for 50 miles., reaching Forest Island. Find the distance between the fishermans's home port and Forrest Islan. Find the bearing from Forrest Island back to his home port. Thanks

February 26th, 2009, 05:32 PM	#2
AnimalCrackers Hardcore Enthusiast 2007 Mustang GT 12.6@110 Join Date: Jul 2007 Location: Kansas City Posts: 2,210 iTrader: 0 reviews	I'm unfamiliar with the manner you're describing his directions. Clarify if you mean 70 degrees West of North, or 70 degrees North of West. ditto for the N-E direction. This should just be simple vectors though. you've got a triangle of 30 miles and 50 miles, so the hypotenuse is SQRT(30^2+50^2) = 58.31 miles. Once you figure out the angle, you're done. __________________ Professor Crackers

February 26th, 2009, 06:04 PM	#6
zinc02GT HUGE RED HEADED DUDE W/FIVE-OH 2011 Mustang GT 12.1 @ 116 Join Date: Dec 2007 Location: Alabama Posts: 5,847 iTrader: 1 reviews	It's just a triangle. If you look ati in your head with images, think of a starting point and you go to X at so many degrees, Then you turn (for example sake) right at so many degrees. Based upon those to point that you have reached with those degrees, whatis the remaining side. That's what it seemed like to me __________________ Mods in garage. Built suspension and gears since posted times.

February 26th, 2009, 06:43 PM	#9
mooses Regular Join Date: May 2008 Posts: 391 iTrader: 0 reviews	Assuming you mean 70* west of north and 10* east of north, I got 48.723 miles at 25.35* east of south. I used law of cosines to get the hypotenuse and the angles... I'd double check my math as I pictured most of it in my head and it could be wrong. edit: actually this is incorrect, I assumed the distance was the hypotenuse of the triangle. I used it as the C in the law of cosines, and since it is not the hypotenuse, it isn't right. Just use an inverse tan like Atlantic Blue said, it'll give you the angle and then you can solve for the length and other angles easily. Last edited by mooses; February 26th, 2009 at 07:15 PM.

February 26th, 2009, 06:47 PM	#11
AtlanticBlue99 I Post Entirely Way Too Much 1999 Ford Mustang V6 14.79 @ 92.15 Join Date: Aug 2005 Location: University of Georgia Posts: 8,854 Blog Entries: 1 iTrader: 0 reviews	It is an inverse tangent function. __________________ ModdedAutos 1999 Mustang V6 I used to list my mods here but stopped when I exceeded 255 characters.

February 26th, 2009, 06:31 PM	#7
mooses Regular Join Date: May 2008 Posts: 391 iTrader: 0 reviews	Keep in mind that you cannot use the pythagorean theorem unless it is a right triangle.

February 26th, 2009, 09:42 PM	#13
Montanasvt Regular 03 10th Ani Cobra Vert 12.20@115 Join Date: Oct 2007 Location: Macon, Ga Posts: 409 iTrader: 0 reviews	Well I got the answer... its not geometry... and its not a right angle... you can only solve right angles using A^2+B^2.... i had to use Law of Cosines and Sines...thanks for all the input guys... the answers where... Distance: 63 miles Bearing : S 162* E

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