Question about determining area of a right triangle, perimeter given, hypotenuse value given in terms of one of the legs.

Hello I have a question about a difficult problem.
The problem states:
Right Triangle- perimeter of 84, and the hypotenuse is 2 greater than the other leg. Find the area of this triangle.
I have tried different methods of solving this problem using Pythagorean Theorem and systems of equations, but cannot find any of the side lengths or the area of the right triangle. I looked for similar problems on StackExchange and around the internet, but could not find anything.
Does anyone know anything that could help find the side lengths of the triangle and the area as well?

Thanks,
William.

are following assertions about linux load and tomcat right?

I am looking to understand precisely how to use the load average and cpu usage on a Red hat machine that hosts a Tomcat 8 only. After looking on the net, I concluded the following assertions. Are the assertions right ? I am deeply sure of the first one since it comes from official Tomcat documentation. And I am confused about which processes could be in uninterruptible sleep.

1) Tomcat uses a thread to process a request, the maximum number of used threads is defined by Tomcat configuration ( see Tomcat documentation )

2) Oracle JVM works with native threads only since JRE 1.3 ( See JVM and threads I did not find an Oracle reference for this point)

3) Linux’s run queue contains processes and threads (id native threads) the same way ( See Linux Load Averages: Solving the Mystery and Wikipedia )

4) Load average provides the average number of process/threads in the run queue ( See Linux Journal )

5) On a Linux machine running a Tomcat only, the load average provides almost the average number of requests.

6) On Linux the load average count process/threads in state running, runnable, and uninterruptible sleep ( See Linux Journal )

7) Process/threads in uninterruptible sleep are waiting for disks I/O, non interruptible locks, network I/O ( See Redhat documenationt that includes network I/O and Linux Load Averages: Solving the Mystery that does not include network I/0 )

The point 7 is not coherent with the reference See Linux Journal that says that “In fact, it is precisely the CPU load that is measured, because load averages do not include any processes or threads waiting on I/O, networking, databases or anything else not demanding the CPU. “.

I understood that if a process reads swap it is in uninterruptible sleep but if it reads a file on internal disk, nfs folder or a SAN bay, is it in uninterruptible sleep ? Red hat documentation listed network, if a process requests a resource on the network is it in uninterruptible sleep ?

Setting the right white balance value

As I understand White Balancing means – making a particular color look as it should have been irrespective of what color the Ambient Light is. i.e A white paper must look white not blueish grey(cool) or orangeish(hot).

So when taking a photo on my DSLR, what I see from the View Finder is same as what my eye naturally sees. However the final photos don’t look good.

I assure you I am having the other settings fine.

As for the White Balance none of the following works perfectly:

  • Auto – In which case it is quite ordinary
  • Preset – Again it does not serve the purpose of making the colors look as they were supposed to
  • Manual – If i am actually setting a color temperature such that a white object looks white to someone who looks at the photo taken, then the other things in the photo looks back. Basically the photo is ruined all together.

So my question is

What should I use as a rule to get it right?

Because when I checked few of the videos on Youtube – They mostly start at a certain value, take the photo, check it and keep increasing or decreasing the temperature and stop at a place where they feel it is right or best (I have no idea how to know what is best)

What is the significance of the three dots “…” on menus and buttons and how to use them right?

Adding three dots after the title of items in a dropdown menu seems to be a common practice (as you can see on the picture of a drop down menu in Google Chrome). They generaly mean that there is “something” after clicking on it.

Google chrome dropdown menu (french version)

These dots are also sometimes presents in the text of action links and buttons.

I am wondering about their utility and relevancy…

In your opinion :

  • What kind of information should be conveyed by these dots ?
  • How and when to use them ?
  • Is it realy relevant to the user, and easily understood by them ?

How to get exposure right in night photography?

In this link there are some wonderful night time scenes (#4,6,7,9,10,11,13). I’m wondering how the photographer got the exposure right. In my experience my camera metering will overexpose everything once it gets darker.

Would the photographer have used a manual setting and just hope it was right, or are there some metering settings that work in low light conditions?

What are the options?

What is right way to get mails from Gmail to Dovecot with doveadm-backup?

Dovecot doc is far from being perfect, thus I’m little bit confused what is right way to get mails from Gmail to local Dovecot.

See: https://wiki.dovecot.org/Migration/Gmail

After some struggle I have working sync of one user but is there something which can be tuned for Gmail and its unusual labels/virtual folders?

Do I understand it right that each gmail user must be synced separately, ie. via a loop as there’s no way to write multiple passwords users file (doveadm backup -F $ file).

IIUC the remote user must be configured in local Dovecot.

I currently have:

# egrep -v '^(#|[ \t]*$  )' /etc/dovecot/conf.d/99-migration.conf                                                                                                                                                                            imapc_host = imap.gmail.com imapc_features = rfc822.size imapc_features = $  imapc_features fetch-headers mail_prefetch_count = 20 imapc_port = 993 imapc_ssl = imaps imapc_ssl_verify = yes imapc_features = gmail-migration  # sed -n '/^namespace inbox/,/^}/p' /etc/dovecot/conf.d/10-mail.conf | \ egrep -v '^([ \t]*#|[ \t]*$  )' namespace inbox {       separator = /       inbox = yes } 

Doing sync:

# doveadm -v -o imapc_user=gmailuser@example.com -o \ imapc_password='gmailuser_password' backup -O '-$  GmailHaveLabels' \ -R -x '\Flagged' -x '\Important' -u gmailuser@example.com imapc: 

And after sync, I got this:

# ls -lF /mail/example.com/data/gmailuser/Maildir/ total 112 drwx------  5 localuser  localgroup    512 Jan 13 22:45 .[Gmail].All Mail/ drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Drafts/ drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Sent Mail/ drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Spam/ drwx------  5 localuser  localgroup    512 Jan 13 22:46 .[Gmail].Trash/ drwx------  2 localuser  localgroup   3072 Jan 13 22:44 cur/ -rw-------  1 localuser  localgroup      6 Jan 13 22:30 dovecot-keywords -rw-------  1 localuser  localgroup   3684 Jan 13 22:43 dovecot-uidlist -rw-------  1 localuser  localgroup      8 Jan 13 22:43 dovecot-uidvalidity -r--r--r--  1 localuser  localgroup      0 Jan 13 22:30 dovecot-uidvalidity.5c3c0276 -rw-------  1 localuser  localgroup  21808 Jan 13 22:44 dovecot.index.cache -rw-------  1 localuser  localgroup   3148 Jan 13 22:44 dovecot.index.log -rw-------  1 localuser  localgroup    240 Jan 13 22:43 dovecot.mailbox.log -rw-------  1 localuser  localgroup      0 Jan 13 22:30 maildirfolder drwx------  2 localuser  localgroup    512 Jan 13 22:43 new/ -rw-------  1 localuser  localgroup    117 Jan 13 22:30 subscriptions drwx------  2 localuser  localgroup    512 Jan 13 22:43 tmp/ 

What is the right way to test website’s backup?

I have a wiki based on dokuwiki. I made a backup of it by archiving all files. I can automate testing it extracting files and manually see that website works. But what is the right way to check that all backup is correct? I thought it should be like that: while making backup script should go to all pages, which it can reach, compute and store the hash of retrieved page. And while testing backup script should do the same and compare hashes. Is it right?

Right click button on surface pen (linux mint)

I’ve installed linux mint 19 on my surface pro 2017. I also bought this pen because it was half the price on the offical microsoft pen and it was stated that it was fully compatible. It actually works fine with a custom kernel, but there are some problem with the 2 keys (right click and eraser).

The right click is recognised by any program (like xev) but it is not mapped to right click in cinnamon or any application. I know that I need to use xbindkeys but I’ve never used it so I don’t know what configuration to use.

I would also like to get a use for the eraser button (maybe use it for ctrl or something like that)

This is the output of xinput.

⎡ Virtual core pointer                      id=2    [master pointer  (3)] ⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)] ⎜   ↳ ipts 045E:001F UNKNOWN                    id=7    [slave  pointer  (2)] ⎜   ↳ ipts 045E:001F Touchscreen                id=9    [slave  pointer  (2)] ⎜   ↳ ipts 045E:001F Mouse                      id=10   [slave  pointer  (2)] ⎜   ↳ ipts 045E:001F Pen Pen (0)                id=13   [slave  pointer  (2)] ⎜   ↳ ipts 045E:001F Pen Eraser (0)             id=14   [slave  pointer  (2)] ⎣ Virtual core keyboard                     id=3    [master keyboard (2)]     ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]     ↳ Video Bus                                 id=6    [slave  keyboard (3)]     ↳ ipts 045E:001F Pen                        id=8    [slave  keyboard (3)]     ↳ gpio-keys                                 id=11   [slave  keyboard (3)]     ↳ gpio-keys                                 id=12   [slave  keyboard (3)] 

Veracrypt system encryption on ssd, do i have to trim the disk right after finishing? how?

i want to encrypt my os that is on ssd (windows 7, x64, mbr partition style).
From what i know veracrypt will encrypt the whole disk, not only the actual data.
not only! it will “fill” the empty space (inside the decrypted disk) with random data to allow hidden os/containers.
This means that the ssd will think that the ssd is full and wear leveling will be limited, thus decreasing the life and speed of the ssd.
can a solution be write in the encrypted disk a very big file that fill the disk and then delete it so that trim will run and mark again most of the disk as empty? will it be one trim operation or more probably many many trim operations (one per sector) that might fill the trim buffer and failing?
does windoes 7 defragment also retrim the disk by sending trim operations at slow speed to allow the disk to process them?
or i have to do nothing and veracrypt will notice that it’s an ssd and encrypt only data and not the whole disk?
can someone point me to a solution inside the veracrypt guide?

What’s the right way to think about a CGF symbol with an infinite null derivation?

I’m curious about the right way to characterize symbol A in a CFG like this one:

A -> A B A -> x B -> y B -> ε // empty 

B is certainly nullable. However, should A be considered nullable? It feels like the answer is probably “no” (and most first-follow implementations I’ve seen either agree or crash on this). However, you can derive an infinitely large parse tree for the null symbol sequence like A -> A(A(A(...) B()) B().