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Foo Off-Topic chit chat with no general subject.

04-11-05, 07:29 PM
#1
phantomcow2
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Im trying to figure out these stupid inverse functions in trig. I know Soh Cah Toa. And im good with that but now its stuff where instead of being given the value of your angle (theta) and the value of one length and you find the rest. Its 2 lengths and you find the angle.
So heres the problem:
A cable 4m long is attached to a pole. This cable is staked to the ground 1.75m from the base of the pole. Find the angle that the cable makes with the ground.
I used the bottom left angle as my theta. I think its the Sin -1 function i have to use since sin is opposite over hypotenuse.

So what i thought to so was Sin -1( 1.75 divided by 4
I came up with 25.94 (rounded slightly)

/ |
4 / |
/ | 1.75
/ |
/ |
/_______|

Can somebody tell me if this is right or not?
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04-11-05, 07:31 PM
#2
phantomcow2
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eeeh the triangle turned out not so great
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04-11-05, 07:32 PM
#3
phantomcow2
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Soh Cah Toa? Smeans Sin. and oh menas opposite over hyp
Cosin and the ah means adjacent over hyp
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04-11-05, 07:34 PM
#4
phantomcow2
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Yea I can photoshop the triangle
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04-11-05, 07:34 PM
#5
phantomcow2
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do you get 25.94 when rounded to the nearest hundred?
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04-11-05, 07:36 PM
#6
phantomcow2
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Soh Cah Toa is what every teacher except this one ***** teaches. For hte intro and the trig class
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04-11-05, 07:41 PM
#7
phantomcow2
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well in geometry class part of the cericulum is intro to trig. Its supposed to be just 4 days. bUt the teacher i have is the biggest math geek ever and is qualified to teach every math course this school offers. He teaches AP stat and trig, and that is what he is more happy with so instead of 4 days we spend 4 weeks
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04-11-05, 07:43 PM
#8
LordOpie
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Originally Posted by MERTON
what's intro?
Use "intro" in a sentence...

Intro.

Phantom is going to intro his boot to Merton's butt.

Intro.

PS: Calc and higher maths are easy if you're solid with algebra and trig

04-11-05, 07:44 PM
#9
phantomcow2
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yea yea i know. IM actually doing well in trig. I enjoy it a hell of a lot more than proofs!
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04-11-05, 07:54 PM
#10
LordOpie
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for those who don't know, curly hair notation = pubic short-hand.

04-11-05, 08:08 PM
#11
ofofhy
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Some Old Horse Caught Another Horse Taking Oats Away

a/sinA = b/sinB = c/sinC, where A is an angle, and a is side of triangle opposite angle A, and so on.

Works for any triangle.

04-11-05, 10:24 PM
#12
apple_quit
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Originally Posted by phantomcow2
Im trying to figure out these stupid inverse functions in trig. I know Soh Cah Toa. And im good with that but now its stuff where instead of being given the value of your angle (theta) and the value of one length and you find the rest. Its 2 lengths and you find the angle.
So heres the problem:
A cable 4m long is attached to a pole. This cable is staked to the ground 1.75m from the base of the pole. Find the angle that the cable makes with the ground.
I used the bottom left angle as my theta. I think its the Sin -1 function i have to use since sin is opposite over hypotenuse.

So what i thought to so was Sin -1( 1.75 divided by 4
I came up with 25.94 (rounded slightly)

/ |
4 / |
/ | 1.75
/ |
/ |
/_______|

Can somebody tell me if this is right or not?

what you actually found was the angle the cable makes the pole. in the picture, you drew 1.75m as the height of the pole, instead of the distance from the stake to the base of the pole. which might have confused you. the answer you found is right for the picture you drew. however, since 1.75 is the base of the triagle...what you're looking for is cos^-1(1.75/4) which should give you ~64.06 deg.

04-12-05, 02:30 AM
#13
anthonaut
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Originally Posted by phantomcow2
Im trying to figure out these stupid inverse functions in trig. I know Soh Cah Toa. And im good with that but now its stuff where instead of being given the value of your angle (theta) and the value of one length and you find the rest. Its 2 lengths and you find the angle.
So heres the problem:
A cable 4m long is attached to a pole. This cable is staked to the ground 1.75m from the base of the pole. Find the angle that the cable makes with the ground.
I used the bottom left angle as my theta. I think its the Sin -1 function i have to use since sin is opposite over hypotenuse.

So what i thought to so was Sin -1( 1.75 divided by 4
I came up with 25.94 (rounded slightly)

/ |
4 / |
/ | 1.75
/ |
/ |
/_______|

Can somebody tell me if this is right or not?
Easy. You make the angle you need to find theta (the angle the cable makes with the ground) and the it becomes:

cos theta = 1.75/4
theta = cos^-1 (1.75/4)

Punch that into your calculator and you're done.

04-12-05, 10:11 AM
#14
operator
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We'll easily solve this problem for you.

Go to paint. Draw out the diagram. Save as jpeg. Upload to any webspace and reference it here.

04-12-05, 11:24 AM
#15
FXjohn
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Originally Posted by phantomcow2
Im trying to figure out these stupid inverse functions in trig. I know Soh Cah Toa. And im good with that but now its stuff where instead of being given the value of your angle (theta) and the value of one length and you find the rest. Its 2 lengths and you find the angle.
So heres the problem:
A cable 4m long is attached to a pole. This cable is staked to the ground 1.75m from the base of the pole. Find the angle that the cable makes with the ground.
I used the bottom left angle as my theta. I think its the Sin -1 function i have to use since sin is opposite over hypotenuse.

So what i thought to so was Sin -1( 1.75 divided by 4
I came up with 25.94 (rounded slightly)

/ |
4 / |
/ | 1.75
/ |
/ |
/_______|

Can somebody tell me if this is right or not?
Just draw it out on Autocad (you said you used) and measure.

04-12-05, 12:19 PM
#16
ofofhy
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Originally Posted by MERTON
you can see the pic just fine if you click on his quote button.
The problem is that the diagram in his original post does not match the wording of the problem. It should be like the attached. Anthonaut and apple_quit are right.

04-12-05, 12:32 PM
#17
ofofhy
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Originally Posted by MERTON
oh. heh. i really need to start reading.
RIF

04-12-05, 01:32 PM
#18
ofofhy
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Originally Posted by MERTON

04-12-05, 02:30 PM
#19
phantomcow2
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i dont need to use autocad. I get it all now,
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04-13-05, 12:27 AM
#20
anthonaut
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Originally Posted by ofofhy
The problem is that the diagram in his original post does not match the wording of the problem. It should be like the attached. Anthonaut and apple_quit are right.
Yay! My Trig teacher would be proud of me.

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