H2office
幼苗
共回答了3个问题 举报
tan1234=tan(8*180-206)=tan(-206)=a
sin(-206)/cos(-206)=a
sin(-206)=acos(-206)
[sin(-206)]^2+[cos(-206)]^2=1
sin(-206)=acos(-206)
[cos(-206)]^2=1/(a^2+1)
cos(-206)=-cos26<0
cos(-206)=-1/√(a^2+1)
所以sin(-206)+cos(-206)=acos(-206)+cos(-206)=-(a+1)/√(a^2+1)
1年前
2