Question

sin a + cos 2a если a=30 градусов

Answer 1

sin 30° + cos 60° = 1/2 + 1/2 = 1

Answer 2

$sin\alpha+cos2 \alpha =sin \alpha +1-2sin^2 \alpha \\ \alpha =30,\,sin30+1-2*sin^230=0,5+1-2*(0,5)^2=0,5+1-2*0,25=\\=1+0,5-0,5=\boxed{1}$