若sinX-cosX=（根号2）/3,0
问题描述：
若sinX-cosX=（根号2）/3,0
答
∵sinx-cosx=√2/3.
(sinx-cosx)^2=2/9.
sin^2x+cos^2x-2sinxcosx=2/9.
2sinxcosx=1-2/9=7/9.
(sinx+cosx)^2=sin^2x+cos^2x+2sinxcosx.
=1+7/9.
=16/9.
即，(sinx+cosx)^2=16/9.
sinx+cosx=±4/3.
∵0
∴sinx+cosx=4/3.
答
(sinX-cosX)^2=4/9
1-sin2x=2/9
sin2x=7/9
(sinX+cosX)^2
=1+sin2x
=16/9
sinx+cosx=4/3
答
(sinX-cosX)^2=2/9
2sinXcosX=7/9
(sinX+cosX)^2=1+2sinXcosX=16/9
sinX+cosX=4/3或=-4/3
因为0