2/sina
Объяснение:
sin^2 (a) + cos^2 (a) = 1
(a-b)^2= a^2 -2ab +b^2
(a-b)× (a+b)= a^2 - b^2
cos^2 (a) = (1-cos2a)/2
2/sina
Объяснение:
sin^2 (a) + cos^2 (a) = 1
(a-b)^2= a^2 -2ab +b^2
(a-b)× (a+b)= a^2 - b^2
cos^2 (a) = (1-cos2a)/2