首先,我们知道sin(a+b)=sina*cosb+cosa*sinb,sin(a-b)=sina*cosb-cosa*sinb我们把两式相加就得到sin(a+b)+sin(a-b)=2sina*cosb所以,sina*cosb=1/2[sin(a+b)+sin(a-b)]同理,若把两式相减,就得到cosa*sinb=1/2[sin(a+b...