问题
填空题
sin(θ+75°)+cos(θ+45°)-
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答案
sin(θ+75°)+cos(θ+45°)-
cos(θ+15°)3
=sin(θ+75°)+cos(θ+15°+30°)-
cos(θ+15°)3
=sin(θ+75°)+
cos(θ+15°)-3 2
sin(θ+15°)-1 2
cos(θ+15°)3
=sin(θ+75°)-[
sin(θ+15°)+1 2
cos(θ+15°)]3 2
=sin(θ+75°)-sin(θ+75°)=0.
故答案为:0.