# Math Help - sec x

1. ## sec x

sec x is undefined for

0 degrees
45 degrees
90 degrees
135 degrees
180 degrees

anyone know this rule want to help me out?

2. Originally Posted by netbook
sec x is undefined for

0 degrees
45 degrees
90 degrees
135 degrees
180 degrees

anyone know this rule want to help me out?
$\sec x$ fails to exist when $\cos x=0$.

What do you think the values are now?

3. could it be for 90 degrees i think the graph of the sec of x has a vertical asymptote at 90 right???

4. Originally Posted by netbook
could it be for 90 degrees i think the graph of the sec of x has a vertical asymptote at 90 right???
Yup, its $90^{\circ}$.

5. Originally Posted by netbook
could it be for 90 degrees i think the graph of the sec of x has a vertical asymptote at 90 right???
even without graph
sec(90)=1/cos(90)=1/0 (as cos(90)=0)
since 1/0 is undefined therefor secx is also undefined for x=90 degrees

6. netbook, look at this. Just click the attachment to enlarge