sina=1/4-sinb sin^2 a=(1/4-sinb)^2cos^2 a=(1/3-cosb)^2相加得1=1/16-1/2 sinb +sin^2 b+1/9 -2/3 cosb+cos^2 b=1/16+1/9+1-1/2sinb-2/3cosb1/16+1/9-1/2sinb-2/3cosb=01/2sinb+2/3cosb=1/16+1/9 ...(1)sin^2 b=(1...