Question

Use an Addition or Subtraction Formula to find the exact value of the expression,
cos(17pi/12)

Answer 1

\[\cos \frac{ 17\pi }{ 12 }=-\cos \frac{ 5\pi }{ 12 }=-\cos (\pi/? + \pi/?)\]

Answer 2

im not sure what to put in for ?'s

Answer 3

What are you in?

Answer 4

math 147 pre cal

Answer 5

Yikes! I have no clue then....

Answer 6

but i have no experience with trig identities, or anything past some algebra.. i took the wrong class :(

Answer 7

its ok im winging it lol

Answer 8

Whatttt that sucks! Im only in geometry and its still hard. Haha alright sounds good lol

Answer 9

i wanna try to solve this problem

Answer 10

i reopened it if you wanna help me with it i got to a point and couldnt find the common denom

Answer 11

ok i m trying

Answer 12

=0. just use calculator

Answer 13

lol k

Answer 14

should i continue to do ur math

Answer 15

sec

Answer 16

working...

Answer 17

sorry not sin it will b cos

Answer 18

let me work it out i think it needs to be simplified more

Answer 19

cos(17pi/12) is the opening post so idk

Answer 20

ya i know

Answer 21

\[\cos(\frac{ 17\pi }{ 12 })=\cos(\frac{ 18\pi-\pi }{ 12 })=\cos(\frac{ 18\pi }{ 12 }-\frac{ \pi }{ 12})\]

Answer 22

\[=\cos(\frac{ 3\pi }{ 2 }-\frac{ \pi }{ 12 })\]

Answer 23

\[=-\sin \frac{ \pi }{ 12 }\]

Answer 24

\[\cos \frac{ 17\pi }{ 12 } = -\cos \frac{ 5\pi }{ 12 } = -\cos (\frac{ \pi }{ ? } + \frac{ \pi }{ ? })\]

Answer 25

\[-\sin(\frac{ 3\pi }{ 12 }-\frac{ 2\pi }{ 12 })\]

Answer 26

it will be a coordinate value on the unit circle

Answer 27

i dont have a value for pi/12

Answer 28

ya u hv a value for -cos(5pi/12). bt its not shown in ur circle

Answer 29

we havent gone that far :/

Answer 30

i think i will b able to solve ur problem in ur way too. can i try

Answer 31

yes sir

Answer 32

ok

Answer 33

i have an answer for sin(19pi/12) = \[-\frac{ \sqrt{6}+\sqrt{2} }{ 4 }\]

Answer 34

\[\cos(\frac{ 17\pi }{ 12 })=\cos(\frac{ 12\pi+5\pi }{ 12 })=\cos(\frac{ 12\pi }{ 12 }+\frac{ 5\pi }{ 12})\]

Answer 35

what is the value of 5pi/12?

Answer 36

cos value i mean

Answer 37

\[=\cos(\pi+\frac{ 5\pi }{ 12 })=-\cos(\frac{ 5\pi }{ 12 })=-\cos(\frac{ 3\pi }{ 12 }+\frac{ 2\pi }{ 12})\]

Answer 38

5pi/12=75 degree

Answer 39

i m going to calculate ur cos(5pi/12). please follow me. i think i will b successful

Answer 40

\[-\cos(\frac{ 3\pi }{ 12 })\cos(\frac{ 2\pi }{ 12 })+\sin(\frac{ 3\pi }{ 12 })\sin(\frac{ 2\pi }{ 12 })\]

Answer 41

following

Answer 42

\[-\cos(\frac{ \pi }{ 4 })\cos(\frac{ \pi }{ 6 })+\sin(\frac{ \pi }{ 4 })\sin(\frac{ \pi }{ 6 })\]

Answer 43

sweet i can work with that one

Answer 44

thanks

Answer 45

i m happy to work with u

Answer 46

-(sqrt(2)/2) x (sqrt(3)/2) x (sqrt(2)/2 x (1/2)

Answer 47

ok i m doing

Answer 48

i think there is a minus in the middle

Answer 49

\[-\frac{ 1 }{ \sqrt{2} }.\frac{ \sqrt{3} }{ 2 }+\frac{ 1 }{ \sqrt{2} }.\frac{ 1 }{ 2 }\]

Answer 50

rationalize the denominators, we dont want roots in the denom :)

Answer 51

\[\frac{ 1-\sqrt{3} }{ 2\sqrt{2} }\]

Answer 52

ya u r right

Answer 53

\[=\frac{ \sqrt{2}-\sqrt{6} }{ 4 }\]

Answer 54

correct! woo hoo thats mohammad

Answer 55

thanks**

Answer 56

u r most welcome

Answer 57

kinda tricky, thanks for your time and work sir

Answer 58

anyway may i know the name of ur country. its just my curiosity

Answer 59

im in the united states

Answer 60

ok

Answer 61

and you?

Answer 62

bangladesh

Answer 63

thats cool its morning there? its late here

Answer 64

ya

Answer 65

its 3.20 pm here

Answer 66

2.20 am here :)

Answer 67

lol

Answer 68

just been grinding this math out lol

Answer 69

i enjoyed ur math too

Answer 70

are you in school?

Answer 71

no

Answer 72

i m a lecturer of physics in national university

Answer 73

wow that must be fun

Answer 74

may b

Answer 75

which languages do you speak?

Answer 76

bangla is my mother language n english is my foreign language. so i m not good in english

Answer 77

its ok i hear english is hard, i speak spanish as my foreign language

Answer 78

i c

Answer 79

do u want to try another question

Answer 80

ya i wanna solve another 1

Answer 81

wanna try

Answer 82

anyway which class u r reading

Answer 83

Use an Addition or Subtraction Formula to find the exact value of the expression, 165 degrees

Answer 84

im in math 147 precalculus it is a hybrid class

Answer 85

studying analytic trigonometry now

Answer 86

i think u will say sin or cos or tan or cot etc.

Answer 87

ok

Answer 88

ur class is unknown to me

Answer 89

that picture is the work of a different, but similar problem

Answer 90

question is not clear to me

Answer 91

is it sin 165

Answer 92

or its cos 165

Answer 93

hmm

Answer 94

oh cos im sorry

Answer 95

its ok

Answer 96

no problem