sin负90度为什么等于负一? 为什么sin90度=1?
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sin-90°=-sin90°=-1
sin90°=1是公理啊。
单位圆里面
sin(-90) = -sin(90) = -1
画个图像看看你就知道了
就是负一,不为什么
绛旓細棣栧厛sin(-x) = -sin(x) 杩欐槸鍏紡 鐒跺悗瑕佺煡閬搒in琛ㄧずy杞翠笂鐨勬暟 鎺ョ潃鐪嬪害鏁版槸90搴 姝f寚鐫Y杞存鍗婅酱 鎵浠ユ槸姝d竴銆愬鏋 鎸囩潃y璐熷崐杞村嵆270搴 灏辨槸璐熶竴銆戙愬鏋 搴︽暟鏄0鎴180 鍗虫寚鐫x杞 涓嶇姝h礋 閮芥槸sin(x) =0 鍥犱负鍦▂杞翠笂 鎸囩潃鍘熺偣 銆戞墍浠in璐90搴︾瓑浜庤礋涓 ...
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绛旓細sin(-90)=-1鎴栬卻in270=-1锛岃繕鏈夊緢澶氬晩銆
绛旓細璐90搴锛岀粓杈瑰湪y杞磋礋鍗婅酱锛屼粠x杞存鍗婅酱椤烘椂閽堟棆杞90搴﹀嵆鏄傚崟浣嶅渾鏄崐寰涓1鐨勫渾锛屽渾蹇鏄鍘熺偣锛sin(-90)搴=-1銆
绛旓細2k蟺+(蟺/2)鏃涓1锛宬涓烘鏁存暟 2k蟺-(蟺/2)鏃朵负-1锛宬涓烘鏁存暟