求函數的單調區間y=3sin（2x+π/4）y=1+sinx y=-cosx是不數正弦余弦前面那些數位、正負號不用管它我想知道原因

y=3sin（2x+π/4）設：A=2x+π/4則有增區間：A[2kπ-π/2,2kπ+π/2]即：2x+π/4 [ 2kπ-π/2,2kπ+π/2]2x [2kπ-3π/4,2kπ+π/4]x [kπ-3π/8，kπ+π/8]同理可推得：减區間為[kπ+π/8，kπ+5π/8]y=1+sinx y=-cosx…