# Give me maths problems!

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• Jun 26th 2012, 04:06 AM
neerajkarn
Give me maths problems!
Hi, everybody!
I am a lover of maths and go crazy to solve any mathematical problem or to discuss any thing about maths. So please feel free to discuss with me.
Looking forward to getting any maths problem soon,

With regards,
Neeraj Karn
• Jun 26th 2012, 04:33 AM
aliciambrissette
Re: Give me maths problems!
I have a trig word problem that has got me stuck. If you could help that would be great. The problem shows a diagram of a street light. The length of the base pole is 28.0ft, the length of the pole connected from base pole to street light is 12.5ft. The angle of the connected poles is 20.0 degrees. How high above the street is the light?
Thank you
• Jun 26th 2012, 05:28 AM
skeeter
Re: Give me maths problems!
Quote:

Originally Posted by aliciambrissette
I have a trig word problem that has got me stuck. If you could help that would be great. The problem shows a diagram of a street light. The length of the base pole is 28.0ft, the length of the pole connected from base pole to street light is 12.5ft. The angle of the connected poles is 20.0 degrees. How high above the street is the light?
Thank you

you've posted this problem once in the trig forum ... please do not double post in another forum.
• Jun 26th 2012, 12:09 PM
zambo34
Re: Give me maths problems!
3. One side of a triangle has length 8 and a second side has length 5. Which of the following could be the area of the triangle?

I 24
II 20
III 5

A. I only
B. II only
C. III only
D. II and III only
E. I, II and III

the answer is d i can get 20 by 1/2 base heigth . but can not figure out how to get 5?
• Jun 26th 2012, 12:37 PM
tomjay
Re: Give me maths problems!
with respect to x differentiate using the chain rule

y = 6 cos (xcubed + 3 )
• Jun 27th 2012, 09:05 PM
lilac52
Re: Give me maths problems!
Can you help with this assignment?
1 Goal
Download data on VIX futures from CBOE and construct a time series of 1-
month constant maturity futures by suitable interpolating and rolling over the
futures contracts.
2 Deliverable
 An Excel workbook with all underlying data, and a daily time series of
1-month constant maturity futures based on
{ High
{ Low
{ Close
{ Settle
 A document containing a description of the VIX futures contract: what
is the underlying, how is it computed, how is it settled etc.
3 Details
The above link contains links to data les for VIX futures from 2004 until now.
You will need to download all data les and process them. Observe that there
is a variety of maturity dates which you will need to consider. With suitably
rolling over I mean that if the maturity becomes to short, say less than 10 days
or a week you will need to switch to the next futures contract. You will need
to interpolate, since the futures contracts have standardized maturity dates,
and you will need to arti cially construct the constant maturity (1 month) by
interpolating between two adjacent maturity dates.
• Jun 27th 2012, 09:28 PM
pickslides
Re: Give me maths problems!
Quote:

Originally Posted by neerajkarn
Hi, everybody!
I am a lover of maths and go crazy to solve any mathematical problem or to discuss any thing about maths. So please feel free to discuss with me.
Looking forward to getting any maths problem soon,

With regards,
Neeraj Karn

Millennium Prize Problems - Wikipedia, the free encyclopedia
• Jun 28th 2012, 12:00 PM
abhishekkgp
Re: Give me maths problems!
Quote:

Originally Posted by neerajkarn
Hi, everybody!
I am a lover of maths and go crazy to solve any mathematical problem or to discuss any thing about maths. So please feel free to discuss with me.
Looking forward to getting any maths problem soon,

With regards,
Neeraj Karn

Can you help me with the Erdos-Faber-Lovasz conjecture? I could not prove or disprove it.
• Jun 28th 2012, 04:14 PM
Deveno
Re: Give me maths problems!
i would like to prove that:

$(\zeta(z) = 0) \wedge (\text{Re}(z) > 0) \implies \text{Re}(z) = 1/2$

i need this fast! (gambling debts. these loan sharks are *so* not understanding my plight.) plz help. kthxbai.

(if you can give me a closed-form expression for $\zeta(3)$, that'll do as a stop-gap, but i need the first one more).
• Jun 28th 2012, 09:58 PM
Prove It
Re: Give me maths problems!
Quote:

Originally Posted by zambo34
3. One side of a triangle has length 8 and a second side has length 5. Which of the following could be the area of the triangle?

I 24
II 20
III 5

A. I only
B. II only
C. III only
D. II and III only
E. I, II and III

the answer is d i can get 20 by 1/2 base heigth . but can not figure out how to get 5?

There are three ways you can evaluate the area of a triangle, namely \displaystyle \begin{align*} A = \frac{1}{2}bh, A = \frac{1}{2}ab\sin{C} \end{align*} and \displaystyle \begin{align*} A = \sqrt{s(s-a)(s-b)(s-c)} \end{align*}, where \displaystyle \begin{align*} s = \frac{a + b + c}{2} \end{align*}.

If the area was \displaystyle \begin{align*} 24 \end{align*}, then it would be possible to have

\displaystyle \begin{align*} 24 &= \frac{1}{2}\cdot 5\cdot 8 \cdot \sin{\theta} \textrm{ (where }\theta\textrm{ is the angle in between the two sides given)} \\ 24 &= 20\sin{\theta} \\ \sin{\theta} &= \frac{6}{5} \end{align*}

This is impossible because \displaystyle \begin{align*} -1 \leq \sin{\theta} \leq 1 \end{align*} for all \displaystyle \begin{align*} \theta \end{align*}.

Can you use a similar process to see if it's possible for \displaystyle \begin{align*} 5 = \frac{1}{2}\cdot 5\cdot 8 \cdot \sin{\theta} \end{align*}?
• Jun 28th 2012, 10:00 PM
Prove It
Re: Give me maths problems!
Quote:

Originally Posted by tomjay
with respect to x differentiate using the chain rule

y = 6 cos (xcubed + 3 )

Let \displaystyle \begin{align*} u = x^3 + 3 \end{align*} so that \displaystyle \begin{align*} y = 6\cos{u} \end{align*}. Then

\displaystyle \begin{align*} \frac{du}{dx} &= 3x^2 \\ \\ \frac{dy}{du} &= -6\sin{u} \\ &= -6\sin{\left(x^3 + 3\right)} \\ \\ \frac{dy}{dx} &= \frac{du}{dx} \cdot \frac{dy}{du} \\ &= 3x^2 \left[-6\sin{\left(x^3 + 3\right)}\right] \\ &= -18x^2\sin{\left(x^3 + 3\right)} \end{align*}
• Jun 29th 2012, 04:39 AM
northdown
Re: Give me maths problems!
I have two expressions for a friction factor that give the same result, but I am having trouble deriving one from another
1/√f = 1.74 -2 Log (2e/D)
F= (1.14 + 2 log(D/e)^-2
Any help would be appreciated.
Thank you
• Jun 29th 2012, 06:21 AM
Prove It
Re: Give me maths problems!
Quote:

Originally Posted by northdown
I have two expressions for a friction factor that give the same result, but I am having trouble deriving one from another
1/√f = 1.74 -2 Log (2e/D)
F= (1.14 + 2 log(D/e)^-2
Any help would be appreciated.
Thank you

Are you sure you copied this down correctly? For example, are you using f and F to mean the same thing? Are you sure they're not supposed to say 1.74 or 1.14?
• Jun 29th 2012, 07:24 AM
northdown
Re: Give me maths problems!
Sorry both should be lower case f, but 1.74 and 1.14 are correct. Both calculations give me same value of f for the ranges of both D and e I tried in an excel spread sheet.
• Jun 29th 2012, 07:44 AM
Prove It
Re: Give me maths problems!
You are also missing a set of brackets somewhere. Is your expression \displaystyle \begin{align*} F = \left[ 1.14 + 2 \log{ \left( \frac{D}{e} \right) } \right]^{-2} \end{align*}, or something else?
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