Question

cosπ/11+cos3π/11+cos5π/11+cos7π/11+cos9π/11

Answer 1

your math teacher must hate youi

Answer 2

whu shud he
i fact i hate him

Answer 3

plsssssssssss.... help me out

Answer 4

i think you can set this equal to say \(x\) and then consider \(2x\sin(\frac{\pi}{11})\)

Answer 5

wht use will it make of...

Answer 6

Hmm, my method does not work, bleh.

Answer 7

What I posted wasn't even right.

Answer 8

bunch of algebra to get
\[2x\sin(\frac{\pi}{11})=\sin(\frac{10\pi}{11})\] and then
\[2x\sin(\frac{\pi}{11})=\sin(\pi-\frac{\pi}{11})\[2x=1\]
\[x=\frac{1}{2}\]

Answer 9

let me see if i can find it for you written out, i can't write out all the algebra, hold on

Answer 10

try this
http://hk.knowledge.yahoo.com/question/question?qid=7008021104348