<span>а) 1+sin a = 2cos²(45°- a/2) 1+sina=2*(1+cos(90-a))/2=1+sina</span> <span>1+sina=</span><span><span>1+sina </span>формула cos²a=(1-cos2a)/2 b) 2sin²(45°- a) + sin 2a = 1 2(1-cos(90-2a))/2+sin2a=1-sin2a+sin2a=1 1=1 c) 1 - sin a = 2 sin²(45°- a/2)
1-sina=2(1-cosa)/2=1-sina 1-sina=1-sina </span>