sinx:上半边正,下半边负;
cosx:左半边负,右半边正;
tanx:1,3象限正,2,4象限负;
cotx:1,3象限正,2,4象限负。
是始边落在
轴正方向,终边按逆时针方向落在坐标平面内的象限角
①第一象限角: ![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/1e30e924b899a901797ab5e610950a7b0308f597?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
②第二象限角: ![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/63d0f703918fa0ec4f4c8add2b9759ee3c6ddb53?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
③第三象限角: ![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/a1ec08fa513d26971358e68d58fbb2fb4216d853?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
④第四象限角: ![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/9f510fb30f2442a7d9af1375dc43ad4bd01302b8?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
其中,
。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/a2cc7cd98d1001e9ab37fddfb50e7bec55e797d3?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
扩展资料:
正弦值在
随角度增大(减小)而增大(减小),在
随角度增大(减小)而减小(增大);
余弦值在
随角度增大(减小)而增大(减小),在
随角度增大(减小)而减小(增大);
正切值在
随角度增大(减小)而增大(减小);
余切值在
随角度增大(减小)而减小(增大);
正割值在
随着角度的增大(或减小)而增大(或减小);
余割值在
随着角度的增大(或减小)而减小(或增大)。
注:以上其他情况可类推,参考第五项:几何性质。