和差化积本+地+生+活+网
2sinAcosB=sin(A+B)+sin(A-B)2cosAsinB=sin(A+B)-sin(A-B)本+地+生+活+网
2cosAcosB=cos(A+B)-sin(A-B)-2sinAsinB=cos(A+B)-cos(A-B)b.d.s.h.5.c.o.m
sinA+sinB=2sin((A+B)/2)cos((A-B)/2cosA+cosB=2cos((A+B)/2)sin((A-B)/2)来源www.bdsh5.com
tanA+tanB=sin(A+B)/cosAcosBtanA-tanB=sin(A-B)/cosAcosB原文www.bdsh5.com
ctgA+ctgBsin(A+B)/sinAsinB-ctgA+ctgBsin(A+B)/sinAsinB本.地.生.活.网原文www.bdsh5.com