Question

Help?
Rewrite with only sin x and cos x.
sin 2x - cos 2x

Answer 1

@jim_thompson5910 @mathmale @Mertsj
Someone please help me.. :(

Answer 2

\[\sin ^2x-\cos ^2x \]
or\[\sin (2x)-\cos (2x)\]

Answer 3

That's what I thought, too. But these are my choices:
2 sinx cosx - 1 + 2 sin^2x

2 sin x cos2x - 1 + 2 sin^2x

2 sin x cos2x - sin x + 1 - 2 sin^2x

2 sin x cos2x - 1 - 2 sin^2x

Answer 4

Come back.. I'm so lost.. :'c

Answer 5

@RadEn @satellite73 @whpalmer4

Answer 6

use these identities :
sin(2x) = 2sin(x)cos(x)
cos(2x) = 1 - 2sin^2 (x)

Answer 7

\[\sin (2x)-\cos(2x)\]appears to be the correct interpretation.

Answer 8

But none of my answer choices match up to that...

Answer 9

Would it be too much trouble for you to tell which interpretation of the problem is the correct one?

Answer 10

What do you mean?

Answer 11

Would it be too much trouble for you to read the first post I wrote?

Answer 12

Actually, I think the way Raden described it gives me answer choice A.

Answer 13

Yes, if you interpret it as \(\sin(2x)-\cos(2x)\) then answer A is correct.

Answer 14

Oh! That's what you were saying. Makes sooooo much more sense now. \[\sin 2x - \cos 2x\] It's not exponents..

Answer 15

A lot of collective time is wasted working problems that people haven't clearly stated, and it's very helpful if you either a) state it unambiguously from the outset, or b) answer questions from people asking "do you mean this, or that" :-)

Answer 16

the problem is that people copy and paste, or don't know any better, and things like \(\cos^2x\) in their problem become \(\cos2x\) on our screens...

Answer 17

My bad. I didn't do it in the equation thing because the way I put it the first time was right. If it has exponents, I will use this thing--> x^2.

Answer 18

I'm just explaining why my colleague might come across as being a bit irritated...you wouldn't like him when he's irritated, so avoid that :-)

Answer 19

Haha. Sorry all. I thought I was clear. Thanks for all of your wonderful help. God bless you.

Answer 20

In general, look at what you write, and ask yourself, "is there any possible way that someone could interpret this in a different fashion than I intend?" If so, add parentheses or use the equation editor (I think most of us assume that if you use the EE, you mean what you write, but no doubt I'll soon waste 15 minutes working a problem where that isn't true :-)

Answer 21

The less time we waste on this, the more time we have to actually help :-)

Answer 22

Haha. :)