Question

高一数学！求大神帮下解答。财富值用完了。

求值:sin(-31π/6)-cos(-10π/3)-sin11π/4 写出详细过程~

Answer 1

sin(-31π/6)-cos(-10π/3)-sin(11π/4)
=-sin(31π/6)-cos(10π/3)-sin(11π/4)
=-sin(5π+π/6)-cos(3π+π/3)-sin(3π-π/4)
=sin(π/6)+cos(π/3)+sin(-π/4)
=sin(π/6)+cos(π/3)-sin(π/4)
=1/2+1/2-√2/2
=1-√2/2
（正弦一、二象限为正，余弦一、四象限为正，其余为负）

Answer 2

sin(-31π/6)-cos(-10π/3)-sin11π/4
=sin(-31π/6+6π)-cos(-10π/3+4π)-sin(11π/4-2π )
=sin(5π/6)-cos(2π/3)-sin3π/4
=1/2 - (- 1/2) - √2/ 2
=1- √2/ 2

没有财富值简单啊

追问

老师算出来是等于2，怎么回事？？