а) cos2a + 2sin^a = cos^2a-sin^2a+2sin^2a = cos^2a+sin^2a=1
б) 1- sin2a*cosa/ 2sina = 1- ((2*sina*cosa*cosa)/2sina) = 1 - cos^2a = sin^2a
а) cos2a + 2sin^a = cos^2a-sin^2a+2sin^2a = cos^2a+sin^2a=1
б) 1- sin2a*cosa/ 2sina = 1- ((2*sina*cosa*cosa)/2sina) = 1 - cos^2a = sin^2a