余弦函数的单调性答:有y=cosx的图像可知[0+2kπ,π+2kπ]k属于z为单调递减区间,[-π+2kπ,0+2kπ]k属于z为单调递减区间,当函数为y=Acos(wx+B)时,(注:w为偶米噶,B为西格玛,都打不来),求单调性,比如求单调递减区间要令t=wx+B,∵y=Acost的单调递减区间为[0+2kπ,π+2kπ]k属于z,∴0+2kπ≤wx+...
怎样求f(x)= cosx的单调递增区间?答:首先要记住 f(x)=sinx的单调增区间是x∈[2kπ-π/2,2kπ+π/2],单调减区间是x∈[2kπ+π/2,2kπ+3π/2],k∈Z f(x)=cosx的单调增区间是x∈[2kπ-π,2kπ],单调减区间是x∈[2kπ,2kπ+π],k∈Z 遇到复合函数时,把ωx+φ看作一个整体,以余弦函数为例,函数简化为f(x)=...