已知sin(3派+@)=1/3,求cos(派+@)/cos@[cos(派-@)-1]+cos(@-2派)/sin(@-3派/2)cos(@-派)-sin(3派/2+@)的值
问题描述:
已知sin(3派+@)=1/3,求cos(派+@)/cos@[cos(派-@)-1]+cos(@-2派)/sin(@-3派/2)cos(@-派)-sin(3派/2+@)的值
答
sin(3派+@)=-sin@=1/3 sin@=-1/3 cos@=±2√2/3
cos(派+@)/cos@[cos(派-@)-1]+cos(@-2派)/sin(@-3派/2)cos(@-派)-sin(3派/2+@)
=-cos@/cos@[-cos@-1]/[cos@(cos@)+cos@]
=-cos@
=±2√2/3