(3SINA-2COSA)/(2SINA+COSA)
分子分母同除以COSA
=(3 TANA-2)/(2 TANA+1)
=8/3.
3SIN^2A-4SINACOSA
=(3SIN^2A-4SINACOSA)/1
=(3SIN^2A-4SINACOSA)/( SIN^2A+COS^2A)
分子分母同除以COS^2A
=(3 TAN^2A-4 TANA)/( TAN^2A+1)
=4.