第2个回答 2019-03-29
因为sinx的单调增区间为(2kπ-π/2,2kπ+π/2)
所以令:2kπ-π/2<π/4-x/2<2kπ+π/2;所以解得-4kπ-π/2<x<-4kπ+3π/2;
所以单调增区间为(4kπ-π/2,4kπ+3π/2)(k为整数)
因为sinx的单调减区间为(2kπ+π/2,2kπ+3π/2)
所以令:2kπ-π/2<π/4-x/2<2kπ+π/2;所以解得-4kπ-5π/2<x<-4kπ-π/2;
单调减区间为(4kπ-5π/2,4kπ-π/2)(k为整数)