化简[sin(2A+B)]/sinA-2cos(A+B)
问题描述:
化简[sin(2A+B)]/sinA-2cos(A+B)
答
[sin(2A+B)]/sinA-2cos(A+B) =[sin(A+B+A)]/sinA-2cos(A+B) =[sin(A+B)cosA+cos(A+B)sinA]/sinA-2cos(A+B) =[sin(A+B)cosA-cos(A+B)sinA]/sinA =sin(A+B-A)/sinA =sinB/sinA