Question

Докажите тождество
sin (α + β) - sin (α – β) = 2 cos α sin β

Answer 1

sin(α+β) - sin(α-β) = 2·cosα·sinβ
sinα·cosβ + cosα·sinβ - sinα·cosβ + cosα·sinβ = 2·cosα·sinβ
2·cosα·sinβ = 2·cosα·sinβ