(派/2)_数学解答 - 作业小助手

(派/2)

人气：460 ℃　时间：2020-03-28 10:13:48

解答

派/20cos(A-B)=12/13
sin(A-B)=5/13
sin(A+B)=-(3/5)
派cos(A+B)=-(4/5)
sin2A=sin(A-B+A+B)=s(A-B)c(A+B)+c(A-B)s(A+B)=-(5/13)x(4/5)-(12/13)x(3/5)=-(56/65)