AS
Alexey Senichev
Будет (+-2cos^2asin^2a)
=cos^4a+2cos^2asin^2a + sin^4a - 2cos^2asin^2a = (cos^2a+sin^2a)^2 - (4*cos^2asin^2a)/2 = 1 - 0,5sin^2(2a)
Ч. т. д.
Ответ. ((cos(a))^2+(sin(a))^2)^2=(cos(a))^4+(sin(a))^4+2*(sin(a)*cos(a))^2=(cos(a))^4+(sin(a))^4+0,5*(sin(2*a))^2=1;
(cos(a))^4+(sin(a))^4=1-0,5*(sin(2*a))^2;