已知cos(a-兀/6)+sina=4/5乘以根號3,則sin(a+7兀/6)的值是?

已知cos(a-兀/6)+sina=4/5乘以根號3,則sin(a+7兀/6)的值是?

cos(A-兀/6)+sinA =√3/2cosA+3/2sinA =√3(1/2cosA+√3/2sinA)=(4√3)/5所以:(1/2cosA+√3/2sinA)=4/5 sin(A+7兀/6)=-sin(A+兀/6)=-(√3/2sinA+1/2cosA)=-4/5