I have a triangular symbol in the icon next to the internet symbol what is it

Adjust the screen resolution

Right click on the icon and select PROPERTIES. There you will see the icon and a box to CHANGE ICON. Click on the CHANGE ICON and you will see where that icon is on your hard drive. You can change another icon to this one by the same method and changing it to the location of the icon you like.

Don't know if it is the same but I discovered that the triangular icon on
my phone screen was there to show that 'Roaming' was on. When I arrived back in UK it disappeared.

the yellow triangular icon with an exclamation mar means that the chat is unable to load try some other browser it some times also happens due to slow internet connection speeds. I recommend Google Chrome or Mozilla Firefox though opera and apple safari browser will also serve the purpose. Where to download them? Just serach them on google.com and you'll get the correct location.

my facebook chat is disabled and yellow triangular icon appears at right on chatting location.

Show the Internet Icon at Taskbar

Right click on Task Bar -> Properties -> Notification Area Tab -> Check Network System Icon Box -> Apply -> OK.

BTW
Symbol=>Icon,
Bottom of the desktop screen=>Taskbar

The function is: f(n) = (n-th triangular number) ^ 2

So, f(1) = (first triangular number) ^ 2

the '^ 2' means "multiply the number by itself", e.g., '3^2' is '9'.

And, f(2) = (second triangular number) ^ 2
and, f(3) = (third triangular number) ^ 2

So, what is a "triangular number" ?

Do an Internet search for "definition triangular number",
and you may find the web-page;

http://www.mathsisfun.com/definitions/triangular-number.html

which gives a definition, plus pictures to help you visualize why they are called "triangular". Hint: a "tri-angle" has 3 sides, while a "quad-rangle" has 4 sides.

On her computer, with the USB plugged in. RIGHT click the computer icon with the yellow warning symbol. It's next to the clock in the lower right hand corner of your screen. Then select "Repair."

I beleive it's the toner, it will need to be changed. You may start to see some fading soon.