化简:cos(π/3+α)+sin(π/6+α)

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/05 18:46:56

化简:cos(π/3+α)+sin(π/6+α)
化简:cos(π/3+α)+sin(π/6+α)

化简:cos(π/3+α)+sin(π/6+α)
这个可以用和差化积的,只不过要先用诱导公式变一下:
比如说都变成sin的
原式=sin(π/6-α)+sin(π/6+α)
=2sin0.5*[(π/6-α)+(π/6+α)] cos0.5[(π/6-α)-(π/6+α)]
=2sin π/6 cosα
=cosα

cos(π/3+α)+sin(π/6+α)
=cosπ/3cosα-sinπ/3sinα+sinπ/6cosα+cosπ/6sinα
=1/2*cosα-√3/2*sinα+1/2*cosα+√3/2sinα
=cosα

把它展开cosπ/3cosa-sinπ/3sina+sinπ/6cosa+cosπ/6sina=cosπ/3cosa+sinπ/6cosa 把cosπ/6换成sinπ/6 这样等于2sinπ/6cosa=cosa