∵sinX-cosX=1/2
(sinX-cosX)^2= sin^2X-2 sinXcosX+ cos^2X =1-2 sinXcosX =1/4
∴sinXcosX=3/8
∴sin^3X-cos^3X
= (sinX-cosX)(sin^2X+ sinXcosX+ cos^2X)
=(sinX-cosX)(1+ sinXcosX)
=1/2×(1+3/8)
=11/16
sinX-cosX=1/2,则sin^3 X-cos^3 X=?
sinX-cosX=1/2,则sin^3 X-cos^3 X=?
RT
RT
数学人气:764 ℃时间:2019-10-03 22:58:44
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