## anonymous one year ago Which function has a domain of all real numbers? A. Y=tanx B. Y=cosx C. Y=1/sinx D. Y= secx

1. sweetburger

is there a difference between B. and C. that I am not seeing?

2. anonymous

I meant Y=1/sinx

3. sweetburger

ok I am pretty sure the domain of y=cosx continues into infinity in both directions+,- only the range is restricted from 1 to -1

4. sweetburger

y= tanx has aymptotes. I think y = secx has asymptotes and I also think that y= 1/sinx has asymptotes as well but Im a bit lazy to look them up.

5. anonymous

Think of it this way:$A. y=\tan x = \frac{ \sin x }{ \cos x }$$B. y=\cos x$$C. y=\frac{ 1 }{ \sin x }$$D. y=\sec x = \frac{ 1 }{ \cos x }$In order for the domain to be the set of all real numbers, there must not exist a real number that would make any denominator equal to zero, as that would lead to an undefined value. Does that help?

6. anonymous

So it would be B, y=cosx?

7. anonymous

Very good.