Question

Rewrite with only sin x and cos x.

cos 2x + sin x

Answer 1

The double angle formula for cosine is cos squared x- sin squared x. There are other ways to write the formula if you need a different answer. Do you think you can work with that?

Answer 2

Do you know the identity for cos 2x. There are two more ways to express cos 2x other than what @L.T. has suggested but I don't just want to give you the answer. I want to teach you how to arrive a the answer on your own. Would you like my help?

Answer 3

yes please

Answer 4

@needinghelpyo I was helping someone else and just noticed your reply. Are you on line right now?

Answer 5

yes

Answer 6

OK to start with do you understand what myself and @L.T. said above and do you know where to take it from there?

Answer 7

no i dont know what the double angle area is its an online class and i dont understand the lesson for this segement

Answer 8

You mean the double angle identities. If you don't know them then here they are. You should know them by heart.
\[\cos 2\theta =\cos ^{2}\theta -\sin ^{2}\]
\[\cos 2\theta =2\cos ^{2}\theta -1\]
\[\cos 2\theta =1-2\sin ^{2}\theta\]
Now how would you use these to answer your question. Any idea?

Answer 9

*that is \[\sin ^{2}\theta\]at the end of the first one.

Answer 10

would the answer be 1+2 sin^2x +sinx?

Answer 11

No, if the answer is to be written purely in terms of sin x. Close but it seems like you made an error somewhere. If you can show me your work then I can help you understand where you went wrong.

Answer 12

i dont know how but then the other one i got is 1+3sin^2x

Answer 13

Didn't you say that you have to write one answer in terms of sine and the other in terms of cosine?

Answer 14

Can you show me your work for the first answer as I asked please?