OpenStudy (en):

please help. find the derivative of z=1/2x+1/4 sin2x. i only got 1/2+1/2 cos2x but my book says cos^2x... pleaaseee

2 years ago
OpenStudy (irishboy123):

use the double angle identity \[cos2x = 2 cos^2 x - 1\]

2 years ago
OpenStudy (en):

is it really necessary to use the cos2x=2cos^2x-1? can i not use 1-2sin^2x which is also equals to cos2x?

2 years ago
OpenStudy (en):

@IrishBoy123 ? pleaaasseee

2 years ago
OpenStudy (irishboy123):

of course you can, go for it see where each takes you, circle back if unsure:p

2 years ago