A=cos1/2
=cos(1-1/2)
=cos1sin1/2+sin1sin1/2
B=cos3/2
=cos(1+1/2)
=cos1cos1/2-sin1sin1/2
C=sin3/2-sin1/2
=sin(1+1/2)-sin(1-1/2)
=(sin1cos1/2+cos1sin1/2)-(sin1cos1/2-cos1sin1/2)
=cos1sin1/2+cos1/2
=2cos1sin1/2
∴A>B>C
A=cos1/2,B=cos3/2 C=sin3/2-sin1/2 ABC的大小关系是什么
1个回答
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