Hello help me please Cos 3pi/6 + 7pi/6
if you mean cos 3π/6 + 7π/6then it is cos π/2 + 7π/6=0+7π/6=7π/6And if you mean cos(3π/6 + 7π/6)=cos(10π/6)=cos(12π-2π/6)=cos(2π-π/3)=cos π/3=0.5
