4*(3/4-(1/4)*cos²α)=4*((√3/2)*0.5-0.5cosα)

3-4cos²α=3-4(1-sin²α)=3-4+4sin²α=(2sinα-1)(2sinα+1)=

(1/4)*(sinα-1/2)(sinα+1/2)=(1/4)*(sinα-sin30°)(sinα+sin30°)=

(1/4)*((2*(sin(α-30°)/2)(cos(α+30°)/2))*2*(sin(α+30°)/2)(cos(α-30°)/2))=

(1/4)*((sin(α-30°))(sin(α+30°))

Bоспользовались заменой 1/2- это sin30°; и формулами

sinα-sinβ=2sin((α-β°)/2)(cos(α+β)/2)

и      sinα+sinβ=2sin((α+β°)/2)(cos(α-β)/2)