Question

Hello! Could someone help me? This is my homework:
8*cos20°*cos40°*cos80°

Answer 1

Famous!

Answer 2

I'm guessing double-angle identity will show up.

Answer 3

yes, I believe but I simply can't work it out

Answer 4

Are u allowed to use any identity?

Answer 5

well, we have been studying identities like "cos2ß=cos^2^ß-sin^2^ß" and so on for some weeks so I believe I only know some basic ones.

Answer 6

OK, http://en.wikipedia.org/wiki/Morrie%27s_law

Answer 7

oh, thank you very much, it's famous indeed!:)

Answer 8

yw:-)

Answer 9

sorry, just one question..is the use of this webpage really free? i've just found it and it's awesome :D

Answer 10

Yup, it's free....