Quadrants confusion

[khurram]

Hi all,

What's meant by:

pi/2+0,-pi/2-0,-pi/2+0.Which quadrants do they lie in?Thanks.

 

[tkhunny]

Not a clue. Can you provide the complete problem statement and maybe the name of the section of the textbook from which you have extracted the problem?

 

[khurram]

While drawing the graph of y=tan x from - pi to -pi

It's written:

"Also we know that tan x is undefined at x=+-90 degrees,when
i) x approaches pi/2 from left i.e,x->pi/2-0,tan x increases indefinitely in 1 quadrant.
ii)x approaches pi/2 from right i.e., x->pi/2+0,tan x increass indefinitely in IV Quad.

iii) x approaches -pi/2 from left i.e., x->-pi/2-0,tan x increases indefinitely in II Quad.

iv) x approaches - pi/2 from right i.e., x-> -pi/2+0,tan x increases indefinitely in III Quad.
I'm unable to understand 'pi/2+0','pi/2-0','-pi/2-0' etc.

 

[tkhunny]

'pi/2+0','pi/2-0','-pi/2-0' etc.

I see. To me, it's sort of funny notation. pka, how standard is this?

"pi/2 + 0" seems to mean something like "just a hair to the right of pi/2"
"pi/2 - 0" seems to mean something like "just a hair to the left of pi/2"

The function doesn't exist AT pi/2, so this some notation for the concept of not-quite-there is required.