Question

[Trigo]
Prove that...
cos^2x+cos^2(x+π/3)+cos^2(x−π/3)=3/2

Answer 1

\[\LARGE \frac{1}{2}(3+\cos2x+\cos(2x+\frac{2 \pi}{3})+\cos(2x-\frac{2 \pi}{3}))\]
I've reached here,dunno what next

Answer 2

maybe cosx+cosy,
that gave me
cos4xcos2pi/3

Answer 3

mai shubham to tag kr rha tha, fir dekha ye to yhi hain. :P

Answer 4

lol

Answer 5

nahi hai :/

Answer 6

abhi to yahin tha. @shubhamsrg

Answer 7

@shubhamsrg ^_^

Answer 8

https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash4/225410_10151288070151370_1115406646_n.jpg

Answer 9

ye cos^2x likhna chate ho ya cos2x ?

Answer 10

rofl! :D

Answer 11

cos^2x :P

Answer 12

haha. mereko milte nhi aise kabhi bhi. :/

Answer 13

cos (square)x ?

Answer 14

yes

Answer 15

snapshot me to cos(2x) hai o.O

Answer 16

http://prntscr.com/watvg

Answer 17

cos2x hai :P

Answer 18

:|

Answer 19

cos(2x + 2pi/3) + cos(2x-2pi/3) = 2cos(2x)cos(2pi/3)

Answer 20

\[\LARGE \frac{1}{2}(3+\cos2x+\cos(4x)\cos (\frac{2\pi}{3}))\]

Answer 21

cos4x kaha se? :|

Answer 22

sorry cos2x

Answer 23

/2

Answer 24

aur bahar 2 bhi hai..

Answer 25

yr shubham, kya besti krta rehta hai meri. :/

Answer 26

:D

Answer 27

No ?

Answer 28

\[\LARGE \frac{1}{2}(3+\cos2x+\cos(2x)\cos (\frac{2\pi}{3}))\]

Answer 29

bahar wala 2 to cancel hogaya @yrelhan4

Answer 30

2cos2x cos(2pi/3) hoga

Answer 31

nahi hoga @DLS

Answer 32

kyun @ParthKohli

Answer 33

kiske saath cancel ho gya?

Answer 34

:D

Answer 35

:nothingtodohere:

Answer 36

OMG. HAHAHAHA.

Answer 37

:o

Answer 38

please don't laugh :)

Answer 39

oh wow! :O
NO.

Answer 40

:P

Answer 41

arreraat ka time hai ~drunk,carry on!!

Answer 42

\[\LARGE \frac{1}{2}(3+\cos2x+2\cos(2x)\cos (\frac{2\pi}{3}))\]

Answer 43

sorry yaar. hasna nhi chahiye tha. :P

Answer 44

cos(2pi/3) rakh do

Answer 45

yes! you got it right! B|

Answer 46

cos(2pi/3) rakh diya. table pe chalega?

Answer 47

arre yaar equation editor sux samaj jao

Answer 48

\(\LaTeX\) khud likh lo, why equation editor?

Answer 49

nahi,table pe nahi :/

Answer 50

The medal belongs the Parth. (Y)

Answer 51

cos2x common kar lo

Answer 52

nahi, it belongs to yrelhan :)

Answer 53

@ParthKohli sabko common room me le jayen?

Answer 54

arre us bechare ka ques kar do pehle -_-

Answer 55

thanks for reminding..

Answer 56

Theek hai, aapke sar pe rakh diya! ^_^

Answer 57

cos raj!

Answer 58

BATAO YAAR KOI :/

Answer 59

Koikkara ko bulayen?

Answer 60

@Koikkara He's calling you.

Answer 61

lol @yrelhan4 same joke :-P

Answer 62

lame*

Answer 63

aaah, bahut bhari hai, hatao ! :(

Answer 64

haha Parth. :P
acha mai chala. krlo solve. bbye.

Answer 65

KAUN SOLVE KAREGA WTF:/

Answer 66

acha iska ans kya hai? :P
matlab kis form me simplify karke lana hai ?

Answer 67

=3/2 prove karna hai? -.- read the fluttering question

Answer 68

Hata diya ^_^

Answer 69

f u c k i n g question*

Answer 70

sex.png! lol..
hahahahhaha
:D

Answer 71

I'm glad you noticed. XD

Answer 72

arre yaar batado fir marate rehna

Answer 73

Accha, help him with the question, phir iss thread mein maze karenge ^_^

Answer 74

kya hoga is duniya ko. sigh
hahaha marate rehna. :P

Answer 75

kya ans hai ?

Answer 76

READ THE F U C K I N G question

Answer 77

Agar answer hoga unke paas toh aapse kyun puchenge? -_-

Answer 78

we have to prove it=3/2

Answer 79

to cos2x common kyu kar liye! :P

Answer 80

Achcha, agar main answer de doon, toh mujhe ek toffee de doge? ^_^

Answer 81

kya drawing hai.. maan gye ustaad.

Answer 82

When you don't know what it is, then freaking Google it!

http://www.answerbag.com/q_view/2665577

Answer 83

galti kardi puchke,rat lenachahiye tha

Answer 84

Now we can enjoy in this thread peacefully :-)

Answer 85

oye, cos(2pi/3) kya hota hai? o.O

Answer 86

and when you get the solution, post it here...
cos(a+b) = cos(a)cos(b)-sin(a)sin(b)

cos(x+π/3) = cos(x)cos(π/3)-sin(x)sin(π/3) = [cos(x)/2]-[sqrt(3)sin(x)/2] = m-n

cos(x-π/3) = cos(x)cos(-π/3)-sin(x)sin(-π/3) = [cos(x)/2]+[sqrt(3)sin(x)/2] = m+n

(m-n)² = m²+2mn+n²
(m+n)² = m²-2mn+n²

(m+n)²+(m-n)² = 2(m²+n²)

So, you have

cos²(x)+2[(cos²(x)/4)+(3sin²(x)/4)] = 3/2

cos²(x)+cos²(x)/2+(3/2)sin²(x) = 3/2

cos²(x)+sin²(x)+cos²(x)/2+sin²(x)/2 = 3/2

1+(1/2)(cos²(x)+sin²(x)) = 3/2

1+(1/2)(1) = 3/2

3/2 = 3/2 check.

Answer 87

:O https://www.facebook.com/permalink.php?story_fbid=313310042125294&id=313109455478686 Is that you?

Answer 88

-1/2 why

Answer 89

cos(2pi/3) = -1/2 and not -sqrt3 /2