sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)=?请问有何简便解法?

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/19 15:39:05
sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)=?请问有何简便解法?
xőJ@_'%nIgM fe?RJCВJ!$EicWqf2] LT•0s|^F3t/Xҁީ)X5E=AU$dc8؆%Y8љG ]xL0m _f$PC!Elעɦq?x]*q\ !X@a/E+St~ܰ5> ]⢚\)8E _QmPe(_lRӱ0刲-'ˬq;n1&

sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)=?请问有何简便解法?
sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)=?
请问有何简便解法?

sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)=?请问有何简便解法?
sin(x-20°)+cos(x+70°)+sin(x+20°)sec(70-x)
=sin(x-20°)+sin(20°-x)+sin(x-20°)/cos(70°-x)
=sin(x-20°)-sin(x-20°)+sin(x-20°)/sin(x-20°)
=0+1
=1

按计算机,代两个数字进去,看看答案想不相同,相同的话,你运气太好了,干对了。
不一样,看看这个答案会和那些角的那个三角有关