求sin105°cos°-cox75°cos105°的值
问题描述:
求sin105°cos°-cox75°cos105°的值
答
sin105°cos°?sin105°cos15°-cos75°cos105°sorry!刚从楼下回来sin105°cos15°-cos75°cos105° =sin105°sin75°-cos75°cos105° =-(cos75°cos105°-sin105°sin75°) =-cos(105°+75°) =-cos180° =-1 祝好 望采纳!