1. f(theta)= sec (theta) ^2

The answer is 2 theta sec^2 tan ^2 theta.

But I got 2sec ^2 theta tan theta.

2. y= sin^2 x- cos^2 x

The answer is 2sin2x.

But I got 4 sinxcosx.

I don't know how to get to these answers. Can someone please help me?

Printable View

- October 25th 2009, 05:48 PMPower of OnePleae help me find these derivatives!
**1. f(theta)= sec (theta) ^2**

The answer is 2 theta sec^2 tan ^2 theta.

But I got 2sec ^2 theta tan theta.

2. y= sin^2 x- cos^2 x

The answer is 2sin2x.

But I got 4 sinxcosx.

I don't know how to get to these answers. Can someone please help me? - October 25th 2009, 05:55 PMChris L T521
- October 25th 2009, 05:58 PMPower of One
- October 25th 2009, 06:01 PMpickslides
- October 25th 2009, 06:01 PMChris L T521
- October 25th 2009, 06:03 PMpickslides
- October 25th 2009, 06:09 PMPower of One
**Thank you guys for reminding me to memorize my trig. identities and double-angle formulas!**

@Chris L T521- I still don't understand the first problem. Using the chain rule,

I would bring 2 to the front minus one a power from sec theta ^2 to be left with sec theta, then multiply by its derivative sec theta tan theta.

What am I doing wrong here? :( - October 25th 2009, 06:17 PMChris L T521
- October 25th 2009, 06:25 PMPower of One
- October 25th 2009, 06:27 PMChris L T521
- October 25th 2009, 06:30 PMPower of One
**I FINALLY UNDERSTAND IT! Thank you so much for being so patient with my stupid self. I really appreciate the help!**