Question Number 103299 by B. H 28 last updated on 14/Jul/20

cos20°cos40°cos80°=...?

Answered by bemath last updated on 14/Jul/20

(1/4) cos 3θ = (1/4)×cos 3.20^o =(1/4)×(1/2) = (1/8)

Answered by Dwaipayan Shikari last updated on 14/Jul/20

(1/(2sin20°))(sin40°cos40°cos80°)=(1/(4sin20°))(sin80°cos80°)=((sin160°)/(8sin20°))=(1/8)