若sinX-cosX=(根号2)/3,0

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/19 20:33:28
若sinX-cosX=(根号2)/3,0
x=n@iBJR+nF$J"ihrD rQF|̌5jw|3ftf~t6f8^."{!"3_}zT U:aKx"T ^T\8sk3~R!.pdCAs(ޔH,

若sinX-cosX=(根号2)/3,0
若sinX-cosX=(根号2)/3,0

若sinX-cosX=(根号2)/3,0
(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

(sinX-cosX)^2=4/9
1-sin2x=2/9
sin2x=7/9
(sinX+cosX)^2
=1+sin2x
=16/9
sinx+cosx=4/3

∵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.
∵00,cosx>0.
∴sinx+cosx=4/3.