RSSKicks
A question from a high school geometry textbook: Imagine a suspension bridge 4000 ft. long. On a hot day the bridge surface expands lengthwise by two feet. The bridge surface remains rigid, except that it rises at the exact middle so that cars have to go up and over a hump. Each half is now 2001 feet long. How far above its normal position does the bridge rise?
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11 Comments, Comment or Ping
boosy
It doesn’t rise, you said that “The bridge surface remains rigid”. i think. don’t quote me
[Reply]
TROUBLMan
Damn. I see no math buff visit the site.
C’mon people. We need an answer.
And you don’t have to show all your work!!!
[Reply]
Q.
it’s a triangle..
the base is 4000 long..
from the starting point to the middle, you have the 2001 measurement..
from that middle point to the end, you have the other 2001 measurement..
geometry allows you to see a triangle where the height is determined by the base (2000) and the other leg of the triangle you already know is 2001.. the simple geometric equation will give you the answer..
am i wrong in my thinking??
[Reply]
"a mom"
two feet.
[Reply]
Heywood
Alright, I’ll take a shot.
As Q said, I’m 99% sure it’s a triangle problem, where we’ve got 2 of the 3 ‘legs’ of the triangle. To calculate the 3rd leg (the rise), we’ve gotta use the Pythagorean Theorem, which states that A^2 + B^2 = C^2. (http://en.wikipedia.org/wiki/Pythagorean_theorem)
In this theorem, C is the hypotenuse, or the longest leg of the triangle (2001ft). ‘A’ would seemingly be the original base (2000ft), so by simple math you’ve got (2001^2) + B^2 = (2000^2), or 4,000,000 + B^2 = 4,004,001. Subtract both sides by A^2 and you’ve got B^2 = 4,004,001 - 4,000,000, or B^2 = 4,001. Take the square root of B^2 and you get B = 63.25ft, the rise of the bridge.
The math checks out, but ~63 feet sounds like a pretty large rise for just an extra foot of expansion on each side lengthwise, so maybe someone else can back me up here, or prove that I know jack shit.
-Haze
[Reply]
BIG Tone
0
[Reply]
boosy
i’m with you TONE.
Shoutout to haze
[Reply]
Q.
Haze..
That’s exactly where i was going with it (with the same answer).. If this is a legit math problem, then the answer is what you (and i) believe.. While the 63′ is high, based on the information given (with the dead center midpoint)..
Now if this isn’t a legit math problem, then shoot, heck if know..
Q.
[Reply]
TROUBLMan
HEYWOOD
I like where your head is at.
You have the correct answer. And despite not having to show all your work you did.
Can the man get a gold star
[Reply]
HEYWOOD
Aww yeah! Big shoutout to Boos, Q, and El Hombre de Apuro
[Reply]
S E V E N
alright man..
my answer is completely on a whole different planet compared to everyone else’s but i’m gonna go with about 1.4..
how the hell did i get that?
well, i looked at the rest of the answers and tried to think of a new solution..
i see the hump as the triangle and the two slopes of the humps as a foot each and mannn . . . . really, i don’t know..
[Reply]
Reply to “Kicks”
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