For the function f(x)=cos(x/6), find all interval(s) where f(x)>0 on the interval (0,24π).
(3π,9π)∪(15π,21π)
(0,3π)∪(6π,9π)∪(12π,15π)∪(18π,21π)
(6π,12π)∪(18π,24π)
(0,3π)∪(9π,15π)∪(21π,24π)
(0,6π)∪(12π,18π)
is it B?
thanks
3 answers
the period is 12π, and f(x) > 0 in the 1st and 4th quarters of each period. so it looks like D to me.
I do not agree with you. x/6 is zero to pi/2 and 3/2 pi to 2 pi, around and around
if x/6 = 3/2 pi
x = 9 pi
this is the only one that starts that way:
(0,3π)∪(9π,15π)∪(21π,24π)
if x/6 = 3/2 pi
x = 9 pi
this is the only one that starts that way:
(0,3π)∪(9π,15π)∪(21π,24π)
Love you guys :)
3 answers