Question

Вычислите sin (a+pi/6) при cos a = -3/5, pi < a < 3pi/2

Answer 1

Sina=-√(1-cos²a)=-√(1-9/25)=-√(16/25)=-4/5
sin(a+π/6)=sinacosπ/6+cosasinπ/6=-4/5*√3/2-3/5*1/2=(-4√3-3)/10