Question

The exact value of cos(7pi/18) is:

Answer 1

is it .99?

Answer 2

I got 1.22 with one repeating

Answer 3

sin(pi/9)

Answer 4

the options are
A. .38
B. .99
C. \[\sqrt{\frac{ 2-\sqrt{2} }{ 4 }}\]
D. \[\sqrt{\frac{ 2+\sqrt{2} }{ 4 }}\]

Answer 5

@Mertsj you can take over XP

Answer 6

So whats the answer?

Answer 7

Do you have a scientific calculator?

Answer 8

yes

Answer 9

cosine pi/9 is .93969 according to my calculator so that eliminates a and b

Answer 10

are you in radians or degrees

Answer 11

I used 20 degrees

Answer 12

wait why are you doing pi/9 when the problem is cos(17pi/8)? Im confused

Answer 13

Because I made a mistake.

Answer 14

oooh lol

Answer 15

is that A,B,C, or D

Answer 16

70 degrees

Answer 17

cos 70=.3420

Answer 18

thats still not an option though. im not sure whether or not to be in radians or degrees

Answer 19

C

Answer 20

It makes no difference.

Answer 21

cos 70 degrees = cos 7pi/18 radians

Answer 22

oh ok. Thank you

Answer 23

yw