tan420度cos750度+sin(负330度)cos(负660度)
=tan(360+60)*cos(720+30)-sin(360-30)cos(720-60)
=tan60*cos30+sin30cos60
= √3* √3/2+1/2* √3/2
=3/2+ √3/4
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tan420度cos750度+sin(负330度)cos(负660度)
=tan(360+60)*cos(720+30)-sin(360-30)cos(720-60)
=tan60*cos30+sin30cos60
= √3* √3/2+1/2* √3/2
=3/2+ √3/4