Trigonometry Question - PeachParts Mercedes-Benz Forum

buffa98 · #1 11-12-2010, 02:07 AM

Hi all, I had to take a math and science test yesterday as part of a pre interview process.

There were several question that I had to use a scientific guess on. One that sticks in my mind is as follows:

You are 300 ft above sea level on a cliff. You see a boat at a angle of 15.9 degrees depression. How far away is the boat?

Is this a sin cos or tan function?

The other stickler was no calculator allowed all long hand. Help please, Some one please explain this to me, It has been a lot of years since I left the classroom.

jt20 · #2 11-12-2010, 02:19 AM

arctan(15.9*)=300/x

---I leap before I look sometimes. This is wrong, and confusing. Sorry. ==> tan(15.9*)=300/x

buffa98 · #3 11-12-2010, 02:31 AM

Quote:

Originally Posted by jt20

arctan(15.9*)=300/x

Which means what? Take the 15.9 divided by the 300 times the Tan of 15.9?

buffa98 · #4 11-12-2010, 02:32 AM

Quote:

Originally Posted by buffa98

Which means what? Take the 15.9 divided by the 300 times the Tan of 15.9?

We were provided a table of sin cos tan with the tests.

jt20 · #5 11-12-2010, 02:37 AM

tan(300/x) = 15.9*

If I had to do it by hand and make a guess, I would start by estimating the 15.9 in terms of pi.

There are only a few values of tangent that people can be expected to remember... you would need a Taylor Series to solve tangent by hand. I don't think any employer is that cruel.

tan=sin/cos and there are a few values of sin and cos that you should kinda know also.

jt20 · #6 11-12-2010, 02:38 AM

Quote:

Originally Posted by buffa98

We were provided a table of sin cos tan with the tests.

oh. gotcha.

then just use the tan(300/x) form

but usually those tables are in radians, so you need to know how to convert. 180*/pi or pi/180*

jt20 · #7 11-12-2010, 02:43 AM

I just found a table that gave each degree in radian form then each trig ratio.

http://cae2k.com/add-photos-to-comment-0/trig-table.html

did your sheet look like that (minus Paris Hilton)?

buffa98 · #8 11-12-2010, 02:45 AM

Quote:

Originally Posted by jt20

oh. gotcha.

then just use the tan(300/x) form

but usually those tables are in radians, so you need to know how to convert. 180*/pi or pi/180*

I came up with 1055 ft. Again trying to remember stuff long filed into I will never need to know how to do this again!!

Is that right?

PS it was for a job at a nuc power plant. I need to pass this one and a 5 part battery to even get an interview!

jt20 · #9 11-12-2010, 02:47 AM

thats purdy darn close 'cordin to my abacus.

x=1053.16

buffa98 · #10 11-12-2010, 03:00 AM

Quote:

Originally Posted by jt20

thats purdy darn close 'cordin to my abacus.

x=1053.16

Close no pic of paris though

jt20 · #11 11-12-2010, 03:01 AM

too bad.

that would be my ideal employer!

cmac2012 · #12 11-12-2010, 03:38 AM

Not to pick but I think sin is the function we want. Tan gives the distance from you to the boat if you were at the same elevation. Sin will get you the hypotenuse of the triangle which is 1095 and small change.

jt20 · #13 11-12-2010, 03:39 AM

just updating from our PM; I didn't take into account the lack of calculator:

Quote:

I don't know how you would use pythg... please enlighten me.

Given the table, I would use the identity of tan.

tan(15.9)=sin(15.9)/cos(15.9)

you want to solve for x so: 300/x = sin(15.9)/cos(15.9)

then, the values for sin and cos are on the table.

then use pythg once you have x: x^2 + 300^2 = hyp^2

hyp = distance to the boat.

you could make a really close estimate at that point. the number I posted was from me using a calculator.

x=1046.4 hyp= 1088.6 using 16* on the table

thank cmac for the correction!

jt20 · #14 11-12-2010, 03:43 AM

Quote:

Originally Posted by cmac2012

Not to pick but I think sin is the function we want. Tan gives the distance from you to the boat if you were at the same elevation. Sin will get you the hypotenuse of the triangle which is 1095 and small change.

ya'know, thats a really good point.

I think I botched this whole thing. Its a matter of semantics, but the boat's distance IS the HYP, not the horizontal leg.

Posting too fast.... get me every time. My apologies.

buffa98 · #15 11-12-2010, 03:57 AM

Quote:

Originally Posted by jt20

ya'know, thats a really good point.

I think I botched this whole thing. Its a matter of semantics, but the boat's distance IS the HYP, not the horizontal leg.

Posting too fast.... get me every time. My apologies.

No apology needed. I sent the PM to explain my pathag answer. I did the rest of the test and came back to these ones.