Member: Melody

921 Questions
34315 Answers

1742

+118725

Mathigon website

I just discovered a site called mathigon

https://mathigon.org/dashboard
read more ..

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Melody Apr 2, 2022

-8

609

+118725

Reporting problems.

There are a number of people having problems at the moment.
If you lodge an error can you please give all relevant information that you can think of.
Where you are in the world - the city or the country - is often very important information. read more ..

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Melody Mar 16, 2022

-2

1459

+118725

How to make an empty rectangle in Latex

I just worked out how to make an empty box of various horizonal size easily in LaTex.
This is not a recommended method, but other methods that I have tried here have not worked.
This coding is really simple. Just put letters inside read more ..

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Melody Mar 15, 2022

-3

871

+118725

HAPPY ANNIVERSARY CHRIS! (CPhill)

I just realized that you became a member here exactly 8 years ago today!

It has been great to have you here all that time

WELCOME BACK CPHILL !

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Melody Feb 11, 2022

-5

717

+118725

Very interesting question. No high level maths required.

This question was posted a couple of days ago.
https://web2.0calc.com/questions/geometry_73561

I think it is really interesting. It looks much more difficult than it really needs to be. read more ..

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Melody Feb 1, 2022

-7

889

+118725

Members have a better experience. Their questions get more attention.

Almost everyone is posting as a guest.
If you post as a member your questions will have a far greater chance of a timely and helpful response.
If you are a genuine learner and interact with us, you will become known and answerers will do read more ..

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Melody Jan 9, 2022

-6

996

+118725

HAPPY BIRTHDAY CHRIS!

Some guidelines for question askers.

Please note:
1) Ask only one question per post.
2) When asking a question talk about what you have tried for yourself. Then people will take you more seriously and will be more able and willing to help.
3) If you get an answer read more ..

off-topic

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Melody Nov 4, 2021

-9

1091

+118725

Remeniscing - a little historical humour.

I just found this old post that some of you, who have been around for a while, might find amusing.

https://web2.0calc.com/questions/look-at-the-new-leader-board

off-topic

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Melody Oct 29, 2021

#91

+118725

Hi everyone,
My last wrap was 3 days ago. I was not really intending to do one tonight. The regular posts were about to 'fall off the page' and I was seriouously considering leaving them there.
Anonymous4338 made me re-think. Thank you for your post on this thread. I am glad I made you happy. You have made me happy too.

Since my last wrap many great answers have been posted by Samgelinas, CPhill, Alan, Kitty<3, reinout-g, brabrams, guest, Rom and Anonymous4338. Thank you.

Samgelinas posted an addictive web game. Thanks for that. I have added the thread address to my collective 'games' thread.

I have written a post 'Information for new members' on the 'Become a member' thread. I have talked about a few things there, I can't actually remember what - You will have to take a look.
I have however explained how the private message system works. Unless you have any particular reason not to, it would be a good idea if you set an alert pop-up for new messages.
I have explained it all in the post. I sometimes want to contact members privately. This is the only way I can do it. Other people may also want to chat.
http://web2.0calc.com/questions/become-a-member-why-would-you-want-to
I think that is it for now.
Stay happy,
Melody.

MelodyApr 4, 2014

+118725

bump

MelodyApr 4, 2014

+118725

bump

MelodyApr 4, 2014

#10

+118725

Calculator for linear regression - suggested by Alan.
http://www.alcula.com/calculators/statistics/linear-regression/

Understanding conics, focus, directric etc interactive graphing.
http://www.intmath.com/plane-analytic-geometry/4-parabola.php

MelodyApr 4, 2014

+118725

bump

MelodyApr 4, 2014

+118725

Dom:
are the lines A(3,4)B(7,7) and C(0,0)D(-6,8) parallel, perpendicular, or neather?

the formula for gradient is (y ₂-y ₁) / (x ₂-x ₁)

so the gradient of AB is (7-4) / (7-3) = 3/4
and
the gradient of CD is (8-0) / (-6-0) = 8/-6 = -4/3

Now the gradients are different so the lines cannot be parallel.
but
3/4 * -4/3 = -1
and this means that the lines are perpendicular.
If two gradients multiply to give -1 then the lines are perpendicular
And, if this is the case then one gradient is the negative reciprocal of the other one.

MelodyApr 4, 2014

+118725

Thank you all, much appreciated

I know a little more about derivatives and a little more about LaTex.
Putting this together was a real struggle.
I can't do chain rule unless I put in 100 extra steps.
This is my LONG version. (expanded from Rom's and reinout-g's - thank you)
Thanks Alan for the last bit. That was easy after all.

LaTex creates files as pdf's and I don't think I can bring pdfs into the forum. What is the best way around this?
I actually rotated this one, snipped it and then rotated it back again but it lost clarity. Also if the output was much longer it still would not have be adequate.

140404 Garage door derivative 2B.jpg

MelodyApr 4, 2014

+118725

Anonymous4338:
RETURN OF ANONYMOUS 4338!
Bet you people didn't expect me to come back!
I got fish by putting a reverse 2 next 2 a regular 2.

A strange looking fish but okay

i am glad that you are back

MelodyApr 4, 2014

+118725

Guest:
How do I solve cosB=.375?

Hi,
when you are looking for an angle you have to use inverse cos or arc cos.
These are different names for the same thing.
the notation is
cos ^-10.375
or
acos0.375

acos(0.375)

With most calculators you will need to press the 2nd function key to get access to cos ^-1 and you don't always need the brackets
Make sure your calc is set to degrees. There will probably be a tiny D at the top of the screen.
so you would press

2nd Cos ^-1 0.375 =

MelodyApr 4, 2014

Username	Melody
Score	118725
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Questions	900
Answers	33647