谁能给我算一下cos120等于-0.5
问题描述:
谁能给我算一下cos120等于-0.5
答
cos120=cos(90+30)=cos90cos30-sin90sin30=0-1X0.5=-0.5
或者:COS120=Sin(90-120)=sin(-30)=-sin30=0.5