# After solving a trig function to find critical points, how do you test them...

• Oct 13th 2012, 12:36 PM
skinsdomination09
After solving a trig function to find critical points, how do you test them...
to see if its a max/min

like if I get 2cosx = 0 at pi/2 (so pi/2 would be my critical point)

do I plug that in back to the original equation? What do I do. Thanks
• Oct 13th 2012, 01:39 PM
skeeter
Re: After solving a trig function to find critical points, how do you test them...
2nd derivative test is easy to do ...
• Oct 13th 2012, 04:58 PM
skinsdomination09
Re: After solving a trig function to find critical points, how do you test them...
What would I do for that?
• Oct 13th 2012, 05:06 PM
Prove It
Re: After solving a trig function to find critical points, how do you test them...
To test if a point is a maximum, the function's second derivative will be negative at that point.

To test if a point is a minimum, the function's second derivative will be positive at that point.

If the second derivative happens to be 0 at that point, you can't state anything.