cos1度+cos2度+… …+cos180度=? 求解,及过程
2013-12-12
展开全部
cos1°=-cos179,
cos2°=-cos178
....
cos89°=-cos91°
原式正负相抵后,仅余下:
cos90°+cos180°=0-1=-1
cos2°=-cos178
....
cos89°=-cos91°
原式正负相抵后,仅余下:
cos90°+cos180°=0-1=-1
2013-12-12
展开全部
解答:
cos1°+cos179°=0
cos2°+cos178°=0
cos3°+cos177°=0
……
即:cos1°+cos2°+cos3°+...+cos180°
=cos90°+cos180°
=-1
cos1°+cos179°=0
cos2°+cos178°=0
cos3°+cos177°=0
……
即:cos1°+cos2°+cos3°+...+cos180°
=cos90°+cos180°
=-1
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