Question

Trigonometry Help!!

Use identities to simplify and show work (remember you are NOT solving for x, just simplifying the expression)

1-2sin^2 x/2

Answer 1

\[\cos x = 1- 2\sin^2 {x \over 2}\]

Answer 2

Can you please show me the steps you took to find that answer. :)

Answer 3

http://www.ecalc.com/math-help/worksheet/trigonometry-identities

Answer 4

shivam are you there? it says your are typing?

Answer 5

where?

Answer 6

\[\cos 2x = \cos (x+x) = \cos x \cos x - \sin x \sin x = \cos^2 x - \sin^2 x\]
Now write cos^2 x = 1-sin^2 x and you will get your answer

Answer 7

In your case , It should be
cos x = cos (x/2 + x/2)=.......

Answer 8

oh? what happened to your long explanation?

Answer 9

That was invalid :D Made some mistake. This is shoreter and easier :D

Answer 10

*shorter

Answer 11

hah..i understand this but are you saying the answer it cos^2x or cos x

Answer 12

@Emilyori , I gave the derivation for cos (2x). Now you try to derive it for cos (x) similarly

Answer 13

i am stuck so would it be \[\cos x \div2 \cos x \div2 - \sin x sinx \] or does the sin change

Answer 14

Shivam...I have to go,, but will return soon...please send me a message to my question if you can...thank you

Answer 15

Make sure you try again by seeing the above example