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11/20/2019 5:07:11 PM [ARCHIVED THREAD] - Math problem > me  Joined Jul 2003 Posts 2279 EE Offline CO, USA Posted: 5/22/2005 2:13:15 PM EST [Last Edit: 5/22/2005 2:16:56 PM EST by IchWarrior] So your standing at the bottom of a water fall, you look up to the top of the falls and for some reason you take not your angle of elevation is 60 degrees.You go hiking 1000 feet away from the water fall, remaining at the same elevation (Okay, better yet you are on a boat and you float 1000 feet down river.You look up to the top of the falls and your angle of elevation is 57.3 degrees.How tall is the falls?Cant for the life of me figger it out.ETA: My only hunches is that you find a ratio of your angles of elevation and multiply that by the 1000 foot difference...  Joined Aug 2004 Posts 348 EE Offline IL, USA  Posted: 5/22/2005 3:42:57 PM EST This is a simple trig problem. The tangent of your angle of elevation is equal to the unknown height of the falls over the distance you are away from it. That is...tan(57.3)=x/1000 solve for x.
 Team Member   Joined Nov 2000 Posts 1402 EE Offline VT, USA  Posted: 5/22/2005 3:47:31 PM EST I'm lazy anymore...ok, maybe I have always been lazy, but I end up just figuring things like this out in a CAD program. "It's good to know who hates you, and it's good to be hated by the right people."
 Originally Posted By Illinigunner21:This is a simple trig problem. The tangent of your angle of elevation is equal to the unknown height of the falls over the distance you are away from it. That is...tan(57.3)=x/1000 solve for x.

i didnt know "simple" and "trig" went in the same sentence.  Joined Nov 2004 Posts 940 EE Offline NJ, USA  Posted: 5/22/2005 3:53:08 PM EST the tangent of an angle = opposite side/adjacent side.Therefore, tangent(57.3) = x/1000 where x=height of waterfallsolve for X
 Resident militant   Joined Feb 2001 Posts 9258 EE Offline WI, USA  Posted: 5/22/2005 4:24:15 PM EST [Last Edit: 5/22/2005 4:31:32 PM EST by drjarhead] Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades. Fuck 'em. We're the ones with the guns. They are not going to stop, ever, until we kick their ass.  Joined Apr 2003 Posts 1870 EE Offline ME, USA  Posted: 5/22/2005 4:26:19 PM EST My answer is "perty damn big"   Joined Jun 2004 Posts 308 EE Offline OR, USA  Posted: 5/22/2005 4:29:55 PM EST [Last Edit: 5/22/2005 4:33:55 PM EST by Aalmeron] law of sinea/sinA=b/sinB=c/sinCa= unknownA=57.3b=1000B=90simple enougha/sin57.3=1000/1a=1000*sin57.3you can finish it from there
 Originally Posted By Aalmeron:law of sinea/sinA=b/sinB=c/sinCa= unknownA=57.3b=1000B=90simple enougha/sin57.3=1000/1a=1000*sin57.3you can finish it from there

Problem is b = a + 1000

 Originally Posted By Aalmeron:law of sinea/sinA=b/sinB=c/sinCa= unknownA=57.3b=1000B=90simple enougha/sin57.3=1000/1a=1000*sin57.3you can finish it from there

Problem is b = a + 1000

dont think so.
but shit, i did make a mistake..

ok

A= 57.3 a=?
B=32.7 b=1000
C=90 c=?

but other than that, the length of b does not equal the length of a plus its own length...

a/sin57.3=1000/sin32.7
a=(1000*sin57.3)/sin32.7
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.
[Last Edit: 5/22/2005 4:53:08 PM EST by Aalmeron]

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.  Joined Jul 2004 Posts 2148 EE Offline VA, USA  Posted: 5/22/2005 4:50:41 PM EST Aw, hell, you're in trig and can't do that? Don't make me get my calculator out...

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

But:

sin R = height of falls/ hypotenuse ::: so I am not sure how that helps.

tan R = height of falls / distance

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

Originally Posted By Aalmeron:

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

With the hyp and the angle you can always get the opposite leg.

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

But:

sin R = height of falls/ hypotenuse ::: so I am not sure how that helps.

tan R = height of falls / distance

so you're using soh cah toa so tangent=oposite over adjacent
tan57.3=x/1000
tan57.3*1000=x which is hte hight of the falls
x=1557.67

[Last Edit: 5/22/2005 5:05:52 PM EST by drjarhead]

Originally Posted By Aalmeron:

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

You are way off.

h is height of the falls or o for opposite side.

You don't use both unkowns. Solve for x using the right side of the equation:

xtan60 = (1000+x)tan57.3

Where x is the distance from the fall. x +1000 is the second distance.

then,

h = xtan60

solve for h.

The Law of sines BTW concerns any triangle, even oblique, with regards to the ratios btwn angles and opposite sides. IOW the ratio of the sin of one of the angles divided by the oppsite side is the same as all the others.

I don't see how it helps.

Gee guys, I haven't done this shit since 1983

 I feel better when I am BELT-Fed   Joined Jan 2003 Posts 1529 EE Offline IN, USA  Posted: 5/22/2005 5:10:20 PM EST Ow my head hurts! The Machine gun is America's best friend as long as it is owned and fired by U.S. Citizens

Originally Posted By Aalmeron:

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

You are way off.

h is height of the falls or o for opposite side.

You don't use both unkowns. Solve for x using the right side of the equation:

xtan60 = (1000+x)tan57.3

Where x is the distance from the fall. x +1000 is the second distance.

then,

h = xtan60

solve for h.

The Law of sines BTW concerns any triangle, even oblique, with regards to the ratios btwn angles and opposite sides. IOW the ratio of the sin of one of the angles divided by the oppsite side is the same as all the others.

I don't see how it helps.

Gee guys, I haven't done this shit since 1983

h = xtan60 doesnt make sence.
where did you get 60?
and x and h are two un knowns

Originally Posted By Aalmeron:

Originally Posted By Aalmeron:

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

You are way off.

h is height of the falls or o for opposite side.

You don't use both unkowns. Solve for x using the right side of the equation:

xtan60 = (1000+x)tan57.3

Where x is the distance from the fall. x +1000 is the second distance.

then,

h = xtan60

solve for h.

The Law of sines BTW concerns any triangle, even oblique, with regards to the ratios btwn angles and opposite sides. IOW the ratio of the sin of one of the angles divided by the oppsite side is the same as all the others.

I don't see how it helps.

Gee guys, I haven't done this shit since 1983

h = xtan60 doesnt make sence.
where did you get 60?
and x and h are two un knowns

The first angle, at distance x, is 60 deg. The second angle at distance 1000 + x is 57.3 deg.
 Originally Posted By IchWarrior:So your standing at the bottom of a water fall, you look up to the top of the falls and for some reason you take not your angle of elevation is 60 degrees.You go hiking 1000 feet away from the water fall, remaining at the same elevation (Okay, better yet you are on a boat and you float 1000 feet down river.You look up to the top of the falls and your angle of elevation is 57.3 degrees.How tall is the falls?Cant for the life of me figger it out.ETA: My only hunches is that you find a ratio of your angles of elevation and multiply that by the 1000 foot difference...

SOHCAHTOA... Resident militant   Joined Feb 2001 Posts 9263 EE Offline WI, USA  Posted: 5/22/2005 5:25:17 PM EST tanR = height / distancetan60 = h / xxtan60 = htan57.3 = h / (1000 + x)(1000 + x)tan57.3 = htherefore:xtan60 = (1000 + x)tan57.3 tan60/tan57.3 = (1000 + x) / x1.11x = 1000 + x 0.11x = 1000x = 1000/0.11= 9091 ft.Therefore:9091 tan60 = 15746ft high falls. Fuck 'em. We're the ones with the guns. They are not going to stop, ever, until we kick their ass.
[Last Edit: 5/22/2005 5:54:52 PM EST by Aalmeron]

Originally Posted By Aalmeron:

Originally Posted By Aalmeron:

Originally Posted By dport:

Originally Posted By Aalmeron:

Originally Posted By dport:
 Originally Posted By drjarhead:Actually, you have use trig and algebra.h = xtan60 = (1000+x)tan57.3Edited cause I don't know my cos from my tan. Rusty. It's been years, hell decades.

Yep, because if you were right under the falls the first angle would be 90 degrees.

ok i dont know what formula that is, but i know the law of sine gives hte right answer.

I can't even remember the law of sine. It's been too long, so you're WAAAY ahead of me.

law of sine gets 1557.67 feet high.

that tangent formula not only has 2 unknowns, but is set to equal the hypotonuse. why are you guys trying to figure out the hyp? he wants the hight of the falls, not the distance from where the person is, to the hight of the falls.

anyway, the hypotonuse is 1851.03 feet tall

You are way off.

h is height of the falls or o for opposite side.

You don't use both unkowns. Solve for x using the right side of the equation:

xtan60 = (1000+x)tan57.3

Where x is the distance from the fall. x +1000 is the second distance.

then,

h = xtan60

solve for h.

The Law of sines BTW concerns any triangle, even oblique, with regards to the ratios btwn angles and opposite sides. IOW the ratio of the sin of one of the angles divided by the oppsite side is the same as all the others.

I don't see how it helps.

Gee guys, I haven't done this shit since 1983

h = xtan60 doesnt make sence.
where did you get 60?
and x and h are two un knowns

The first angle, at distance x, is 60 deg. The second angle at distance 1000 + x is 57.3 deg.

oh crap, you're right.

lets do it this way.

C=90
c=who cares

A1=60
a1=what we want (w)

B1=30
b1=x

A2=57.3
a2=w

B2=32.7
b2=X+1000

since using hte law of sine on both of these gives...

w/sin60=x/sin30
w*sin30/sin60=x

w/sin57.3=x/sin32.7
w+1000*sin32.7/sin57.3=x

w*sin30/sin60=w+1000*sin32.7/sin57.3
.577w=.477(w+1000)
1.2087w=w+1000
.2087w=1000
w=4790.87feet

which doesnt look right
 Originally Posted By Doctor_Chicago:Ow my head hurts! +1,000,000,000    Originally Posted By drjarhead:tanR = height / distancetan60 = h / xxtan60 = htan57.3 = h / (1000 + x)(1000 + x)tan57.3 = htherefore:xtan60 = (1000 + x)tan57.3 tan60/tan57.3 = (1000 + x) / x1.11x = 1000 + x 0.11x = 1000x = 1000/0.11= 9091 ft.Therefore:9091 tan60 = 15746ft high falls.

looks good to me...  Joined May 2004 Posts 446 EE Offline MI, USA  Posted: 5/22/2005 6:00:26 PM EST I get 15,470.7 feet.
 Originally Posted By danno-in-michigan:I get 15,470.7 feet.

That would be more correct. I dropped a few digits during my calcs.
 Originally Posted By danno-in-michigan:I get 15,470.7 feet.

I confirm with this number  [ARCHIVED THREAD] - Math problem > me Top Top