Urgent! Need help or will fail Geometry!

[Twilight_Overlord]

Two vertical poles have heights 6 ft. and 12 ft. A rope is attached from the top of each pole to the bottom of the other. How far above the ground do the ropes cross?

[dAnceguy117]

~3.14159265 km^2

[Kilgamayan]

Your problem is impossible to solve without knowing how far apart the poles are.

[Squeek]

Somehow I think we need to know how spaced out the poles are.

In any event, doing this in the lamest way possible, the result from drawing it in Paint says 4.2 feet. Then again, I have no idea how many feet were between the poles I used.

~Squeek

[jamuko]

Nope, distance between poles doesn't matter.

I can solve it algebraically, or by cheating with graph paper XD but I've forgotten how to do this the geometric way.

The answer is 4 ft.

[Kilgamayan]

Oh, you're right. I was doing it graphically and kept getting different x values, but y would be the same every time because the functions change at the positions of the poles do.

Duh. ._.

[jamuko]

Hehehe.

Okay, I think I've gotten it the way your teacher probably wants you to know it.

Because distance doesn't matter, let's just say it's 1 to be easy.

So it looks like this:


We are looking for h.

Notice how h forms triangles that are similar to the triangles made by the poles: triangle ACF is similar to ADE, and ECF is similar to EBA.

Knowing this, we can use tangent ratios to solve. tangent(angle) = opp.side / adj.side

tan(x) = h / AF
tan(x) = 6 / 1

Solve between those, and you get h = 6*AF.

Now... other triangle!

tan(z) = h / FE (Fire Emblem lololol)
tan(z) = 12 / 1

Solve between those to get h = 12*FE.

Now look at our two equasions for h.

h = 6*AF
h = 12*FE

We know AF + FE = 1.
So AF = 1 - FE

Substitute...

6*(1 - FE) = 12*FE

Solve and we get FE = 1/3.

Substitute into h equasion...

h = 12*(1/3)

So finally,
h = 4.

Phew.
Mm, geometry.

[Squeek]

Oh.

See, as soon as you use trig functions, I go "what"

I never took Trig. It makes Calculus very fun.

=(

~Squeek

PS - I was close =x

PPS - For future reference, don't ask us. We're not homework help. Call a friend. Just so happens us three were bored and you gave us something to fill very few minutes of our time.

[jamuko]

Ouch =x

Trig/precalc was the time everything all started to click for me. It's confusing as heck at first, but once you get a grasp on what it's all about, it's like you've become enlightened on mathematics and everything finally makes sense all together. XD At least that's how it was for me.

Although I always did like geometry for some reason. Playing with spacial math is yummy fun.

The way you use trig ratios in geometry is pretty easy. It doesn't go into all the confusing stuff with sin waves and all that. All you need to know for geometry is the ratio for each ("SOH CAH TOA"). It's more handy than hard. =D

Gah. I dunno why I'm so blabbery about math right now... I must be craving it since I haven't had a single math course all year >_>

[Moogy]

kefit how do u program java

[lightdarkness]

4

[Kefit]

Originally Posted by Moogy

kefit how do u program java

with trig

at least i think i needed trig when i made my 3d rotating nodal structure. i'll have to check

[Squeek]

omg shut up plz

I'm back in CS this year. I swear I won't ask you for help since it's just more material you can use in a0 chats or with Moogster.

~Squeek

[jamuko]

The Squeek abuse wounds me, guys.

[Moogy]

Originally Posted by MrESqueek

omg shut up plz

I'm back in CS this year. I swear I won't ask you for help since it's just more material you can use in a0 chats or with Moogster.

~Squeek

#a0.com has been dead for months (and most of us have been banned from a0.com for months)

#machogang is where it's at

[aperson]

Originally Posted by Kilgamayan

Oh, you're right. I was doing it graphically and kept getting different x values, but y would be the same every time because the functions change at the positions of the poles do.

Duh. ._.

C'mon dude, do a bit of functional analysis and it should be plain as day that the y scalar of the function doesn't change.

[Kilgamayan]

Hey it was late and I wasn't thinking properly :(

[lord_carbo]

Rofl, we were JUST learning stuff like this last week, damnit Jamuko I wanted to look smart.

This is like Algebra I stuff, rofl, geometry?

[Brainmaster07]

The problem doesn't require trig. Assuming distance d and hieghts h(1) and h(2).

You are looking for y at intercept x, set equations equal to x. You need to do this because x is dependant on d, while y is not.
x = (yd)/(h(2))
x = -((y - h(1))d)/(h(1))
If you want to know where I got that, just use some logic. Rise over run times x and negative rise over run times x plus the hieght.
y = (h(2)/d)x
y = -(h(1)/d)x + h(1)


Equate the system of equations to get the general equation
-(y - h(1))/(h(1)) = y/(h(2))
-(h(2)(y-h(1))/h(1) = y
h(2) = y + (h(2)y)/h(1)
h(2)h(1) = h(1)y + h(2)y


Now it's easy, plug in the values
12*6 = 6y + 12y
72 = 18y
y = 4

that general equation will get you the answer for any hieghts, and the distance doesn't matter (Notice it canceled after the substitution). I just perfer to solve problems that way, sorry if it's a bit messy.


Also,

Originally Posted by MrESqueek

Oh.

See, as soon as you use trig functions, I go "what"

I never took Trig. It makes Calculus very fun.

Woah woah woah, what calc are you in? I can see maybe getting through calc 1 without much knowledge of trig (The focus is much more on derivatives and integrals) but anything past that would be a heck of a lot of fun... Especially those triginometric substitutions, which use trig identities, trig integrals and basic trig manipulations along with everything you've learned about integrals to that point in calc 2 (7.5 in my book). I actually really enjoy those problems, but I'm a nerd .

[Kilgamayan]

He may be in Business Calc. I know our school offers two Calc I/II sections - 133/134, Calc for math/CS majors/engineers, and 123/124, Calc for Business/CJ/Psych/whathaveyou majors. 123 and 124 don't cover Trig at all, but otherwise the two curriculi are exactly the same.