Question

√2*соs^2*7pi/12-√2*sin^2*7pi/12

Answer 1

cos^2 a - sin^2 a = cos 2a, поэтому

V2*(cos^2 (7pi/12) - sin^2 (7pi/12)) = V2*cos (7pi/6) = V2*(-V3/2) = - V6/2