淮河岸边是家长
幼苗
共回答了22个问题采纳率:95.5% 举报
(sin450°-α)-sin(180°-α)+cos(450°-α)+cos(180°-α)
=sin(360°+90°-α)-sinα+cos(360°+90°-α)-cosα
=sin(90°-α)-sinα+cos(90°-α)-cosα
=cosα-sinα+sinα-cosα
=0
sin(-23/6π)+cos13π/7xtan4π-cos13/3π
=sin(4π-23/6π)+cos(6π/7+π)xtan4π-cos(4π+1/3π)
=sin(1/6π)-cos6π/7x0-cos1/3π
=1/2-0-1/2
=0
1年前
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