高一数学,14题,加步骤,谢谢

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高一数学,14题,加步骤,谢谢
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高一数学,14题,加步骤,谢谢
高一数学,14题,加步骤,谢谢

 

高一数学,14题,加步骤,谢谢
题目是 tan1234°=a,那么sin(-206°)+cos(-206°)的值为
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

[sin(-206)]^2+[cos(-206)]^2=1sin(-206)=acos(-206)[acos(-206)]^2+[cos(-206)]^2=1a^2[cos(-206)]^2+[cos(-206)]^2=1(a^2+1)[cos(-206)]^2=1[cos(-206)]^2=1/(a^2+1)

等着啊!给你拍个图

同学,tan1234=tan154=a
sin(-206°)=–sin(154°)
cos(–206°)=cos(154。)