函数y=|cos(x+3π)|的单调增和减区间
主要内容:
根据三角函数性质,结合绝对值有关性质,介绍绝对值三角函数y=|cos(x+3π)|的单调增和减区间。
去绝对值步骤
1.当cos(x+3π)≥0,此时y=cos(x+3π),
自变量x的取值范围计算如下:
2kπ-π/2≤x+3π≤2kπ+π/2,k∈Z。
2kπ-π/2-3π≤1x≤2kπ+π/2-3π,
(4k-7)π/2≤x≤(4k-5)π/2,
2.当cos(x+3)<0,此时y=-cos(x+3),
自变量x的取值范围计算如下:
2kπ+π/2<x+3π<2kπ+3π/2,k∈Z。
2kπ+π/2-3π<x<2kπ+3π/2-3π,
(4k-5)π/2<x<(4k-3)π/2,
三角函数的单调区间
1. 当y=cos(x+3π)时,
在(4k-7)π/2≤x≤(4k-5)π/2区间上,
取x+3π=2kπ+0,则x=(2k-3)π,
增区间为:[(4k-7)π/2,(2k-3)π];
减区间为:[(2k-3)π,(4k-5)π/2].
2.当y=-cos(x-3π)时,
在(4k-5)π/2<x<(4k-3)π/2区间上,
取x+3π=2kπ+π,则x=(2k-2)π,此时有:
增区间为:[(4k-5)π/2, (2k-2)π);
减区间为:((2k-2)π, (4k-3)π/2].
综上所述,此时绝对值函数y=|cos(x+3π)|的单调区间为:
单调增区间为:
[(4k-7)π/2,(2k-3)π],[(4k-5)π/2, (2k-2)π);
单调减区间为:
[(2k-3)π,(4k-5)π/2],((2k-2)π, (4k-3)π/2]。
特别声明:以上内容(如有图片或视频亦包括在内)为自媒体平台“网易号”用户上传并发布,本平台仅提供信息存储服务。
Notice: The content above (including the pictures and videos if any) is uploaded and posted by a user of NetEase Hao, which is a social media platform and only provides information storage services.