设tan1234度=a,那么sin(-206度)+cos(-206度)的值为
问题描述:
设tan1234度=a,那么sin(-206度)+cos(-206度)的值为
答
tan1234=tan(8*180-206)=tan(-206)=asin(-206)/cos(-206)=asin(-206)=acos(-206)[sin(-206)]^2+[cos(-206)]^2=1sin(-206)=acos(-206)[cos(-206)]^2=1/(a^2+1)cos(-206)=-cos26