## Trigonometry – confusion when looking for solutions to trigonometric problems within a range

I have recently had problems with the solutions proposed for trigonometric problems. For example, there is a case like 2 + 3cos 2x = 0. For all trigonometric problems in any form, I know that I have to use algebra or trigonometric identities to isolate them x or theta or isolating a single trigonometric function with a single angle corresponding to a value on the right before finding all solutions. However, I am confused about the answers to many trigonometric problems. In the above example, it is limited to the range of x is less than or equal to 180 and greater than or equal to 0. Resolve for xI get -20.9 degrees. I see that this is out of range, but if I take the reflection amplitude of that answer (+0.36), I see that a line drawn in the graph of the Sin function intersects the function at two points one is +20.9 degrees and the other is 159.1 (180-20.9) degrees. But in my textbook it says that 110.9 degrees are the answer.

For this reason, I would appreciate any help that helps me understand how to find all solutions to a problem in a limited capacity. I have solved many of these trigonometric problems, but when I come to the point where I have to specify the solutions that will satisfy such problems, I am completely lost. I looked at several videos and read online tutorials on this topic in mathematics, but I can not see their reasons for multiple solutions.

## Calculus – Washer method confusion

Calculate the volume of the volume created by rotating the bounded area $$y = sqrt x$$, $$y = 0$$ $$x = 1$$, $$x = 4$$around the y-axis.
I understand that I can find the volume by integrating the volume $$A (y)$$ from $$0$$ to $$2$$ since these are the ones $$y$$ Values ​​of the sections of $$x = 1$$ and $$x = 4$$,

My understanding is that I would calculate the range $$(A (y)$$by:
$$pi$$ $$(R ^ 2) -r ^ 2)$$ from where $$R$$ is the outer radius and $$r$$ is the inner radius. Then I integrate that as $$int_0 ^ 2 A (y) dy$$,

So I calculate the outer radius $$R$$ by calculating the $$x$$ Distance from the rightmost border, in this case $$x = 4$$ and the $$y$$ Axis. Thus $$R = 4$$, Is that the way to calculate? $$R$$ even if part of the $$R$$ $$x$$ Distance is not within the limit? Ugh, confused about the definition here.

The inner radius is the $$x$$ Distance from the function to the rotation axis (the $$y$$ Axis). So, $$r = y ^ 2$$,

But I would think that this distance X is ONLY in the region of $$x = 1$$ and $$x = 4$$, Since I should always calculate from right to left, this radius would not be that way $$y ^ 2-1$$??

I can not seem to understand this washing problem, though I can handle others, and I can see that I do not fully understand the definition of calculating inner and outer radii.

Can someone clarify that? The bottom line is that I can not properly calculate the inner and outer radii of this problem.

## Confusion about "unloadwallet"

I do not know how unloaded wallets behave in Bitcoin Core v0.17.0.1.

If I create a new wallet with `Createwallet`, add with a recipient address `import multi`and then unload it `unload wallet`:

1. Will bitcoind continue to recognize payments to the address (es) of this wallet? (seems yes)
2. If so, this detection will only be done when used `loadwallet` once again? (seems yes)
3. If so, does this require rescanning (last) blocks? (I'm worried how long that might last if I loaded this wallet for the last time months or years ago.)
4. If so, is that a problem on a cropped knot?
5. If so, should I avoid this multi-wallet feature on a truncated node, or is there a safe way to use it without risking large downloads? (never unloaded, for example)

## Linear algebra – Confusion of the GMRES algorithm

The book Numerical Linear Algebra by Trefethen presents the GMRES algorithm as follows:

As far as I understand, one should repeat the loop from n = 1 to n = m, where $$m times m$$ is the size of the quadratic input matrix $$A$$ and $$m$$ is the size of the vector $$b$$ in the $$Ax = b$$, With each step $$n$$ Arnoldi enters $$(n + 1) times n$$ Hessenberg matrix. In minimization step one $$QR$$-Factors $$H_n$$ and solves the minimization problem by back-substitution and then checks the norm of the residual for the convergence condition.

What if, after that? $$m$$ Steps is the convergence condition not met? What do we do?

Whatever, if the convergence condition is fulfilled in $$n Steps? Then the last vector $$x$$ will have a dimension $$n is not that true? How do I handle this?

And why do we need it eventually? $$x_n$$ at every step, if it is not used in a subsequent step?

Please help me to understand what is going on in this algorithm since I have spent many hours and this still seems vague to me.

## Confusion about min-cut probabilities

• There is currently a video on Counting Minimum Cuts by Tim Roughgarden.
• $$(A_ {i}, B_ {i}) = big ((A_ {1}, B_ {1}), …, (A_ {t}, B_ {t}) big) forall i in Bbb {R}$$
• $$P big ((A_ {i}, B_ {i}) big) geq frac {1} { begin {pmatrix} n \ 2 end {pmatrix}} = p$$What I interpret as the lower bound of probability to have at least a minimal cut.
• In the following problem group, the two answers A and B are marked as correct. I understand why A is right. But I am confused why B is also marked as correct.
• A: For every diagram $$G$$ With $$n$$ Knots and every min-cut $$(A, B)$$ (I assume that $$(A_ {i}, B_ {i})$$) $$P big ((A, B) big) geq p$$,
• B There is a graphic $$G$$ With $$n$$ Knots and a min-cut $$(A, B)$$ (again the same as $$(A_ {i}, B_ {i})$$) from $$G$$ so that $$P big ((A, B) big) leq p$$,

## Performance – Python Numpy: Confusion – why go through in numpy

I'm programming for 2 years in pure Python.

Now I'm learning Numpy and I'm confused.

Tutorials have shown that Numpy is much more efficient than pure Python. Given examples, but if I try simple iteration for example:

``````import numpy as np
import time
start = time.time ()
List = Range (1000000)
array = np.arange (1000000)

for item in list:
consist
print (& 39; + str ((time.time () - start) * 1000) + & # 39; n & # 39;)
start = time.time ()
for an element in np.nditer (array, order = & # 39; F & # 39;):
consist
print (& 39; + str ((time.time () - start) * 1000) + & # 39; n & # 39;)
``````

I received an issue:

87.67843246459961

175.25482177734375

As you can see above, iteration over Numpy is less efficient than pure Python.

My question is: I do not understand and can not explain why Numpy and Moreso are used: When should I use it?

## Callback Pattern – Return Value Confusion

I have a `EinschränkungenResolver` Class that solves a queue of `force`s. This happens when a `EinschränkungenResolver` Property Views `meetConstraint ()` on one `force` on.

Most of `meetConstraint ()` Implements are returned immediately, so I could just return a Boolean, but there is at least one blocking, which means I need to implement the callback pattern.

Do I have the ability to combine both solutions, or do I just need to implement the callback pattern?

ps: I was not sure if this question had to be asked here or StackOverflow

## 301 redirect confusion | Web Hosting Talk

I have a client for whom I have created dozens of pages of links to a particular webinar site over the years. This site has just been shut down, so I need to redirect all these old links to a temporary page of the site until we have time to restore things to another service. The problem is that I do not seem to be able to get the htaccess forwarding going, so I hope somebody can help me.

The broken URLs all start with https://app.webinarjam.com

I'd like to rewrite all the URLs on the site so that this URL will be rewritten anywhere on https://mysite.com/temporarypage.php

I thought of doing something like that

Redirect 301 https: //app.webinarjam.com* https://mysite.com/temporarypage.php

would work, but this will cause the site to issue an error 500 wherever a webinarjam link is displayed. How should I perform this forwarding?

## Confusion in directory submission

Hello experts, for my blog I would like to submit a directory. I've found many directory submission sites, but a bit of confusion, there are many sites and blog and web directories available in this list. Both are the same or different. Can I paste my blog link into web directory pages?

## 1672 websites surfed in one day

This is a discussion about 1672 websites surfed in one day within the Advertising & Marketing Forums, part of the Internet Marketing category; As of January 14, 2016, I had 1672 websites with easyhits4u.com (local transport office) but no sales from my internet marketing.

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