Question

Can this be simplified?

cos(180° + x) + cos(180° - x)

Answer 1

yeah !!!

Answer 2

2cos((180+x+180-x)/2)cos((180+x-180+x)/2) = 2*(-1)*cosx = -2cosx

Answer 3

@Katieholmes

Answer 4

hint: use sum and difference identity for cosine

Answer 5

well that hint leads to another way to go about this
i'm trying to determine what identity you used @princeharryyy
i'm not saying it is wrong
i just want to know the identity
and also it might be important to the asker what identity you used

Answer 6

cosA+cosB = 2cos((A+B)/2)cos((A-B)/2)

Answer 7

@myininaya

Answer 8

there's another soln as well but this one is the most easiest one :)

Answer 9

well the sum and difference identities are pretty easy to use

i haven't used the identities you mentioned in awhile
good strategy though

Answer 10

u can also use cos(A+B) and cos(A-B) identities to solve the problem @myininaya

Answer 11

can you tell me out of this chart which im using?

Answer 12

wat do you want to know in this

Answer 13

which identity im using to solve this equation

Answer 14

ive never seen one like this so im a bit confused

Answer 15

how would i know which one u are using :D
trignometry is too easy if u know as much of them as u would

Answer 16

if u want u can have link of the properties @Katieholmes

Answer 17

yes please :)

Answer 18

wait a sec

Answer 19

u can have this for ur reference @Katieholmes ...
thogh there are many others but i think this would be sufficient for u

Answer 20

???? hey dere ???

Answer 21

so it would be the second product identity?

Answer 22

sum to product one in the last :)

Answer 23

okay so cos+cos

Answer 24

the earlie one that u said is just the extension of the last one they are one of the same if u look closely to them u don't need to remember both of them they are actually same see closely :p

Answer 25

earlier*

Answer 26

okay thank you!

Answer 27

try and feel maths is pretty easy just improve your speed...
u r better than others .... nd hardworking ofcourse

Answer 28

@Katieholmes

Answer 29

haha thank you so the final answer would be -2cosx

Answer 30

yeah and now i am feeling sleepy ...
it's 2:15 am so talk u later bieeee @Katieholmes

Answer 31

bye haha and thank you

Answer 32

:p

Answer 33

welcome