Asked by Anonymous

lim as x approaches 0
(1-Cos^2(3x))/x^2

How do I derive the numerator??
Answered by Reiny
derivative of 1 - cos^2 (3x)
= derivative of 1 - (cos(3x))^2
= -2cos(3x) (3)(-sin(3x)
= -3(2sin(3x)(cos(3x))
= -3sin (6x)
Answered by Anonymous
Is that Chain rule you used? Or..
Answered by Reiny
yes, that's why I wrote it as (cos(3x))^2 , so you would see it that way
Answered by Anonymous
Is it a double chain?