2cos(2альфа+2П/3)/2 * cos(2альфа- 2П/3)/2=

Question

2cos(2альфа+2П/3)/2 * cos(2альфа- 2П/3)/2=

Answer 1

(4*cos(2*alpha)^2-3)/8

(2*cos(4*alpha)-1)/8

Answer 2

(4*cos(2*alpha)^2-3)/8

(2*cos(4*alpha)-1)/7