函数y=3sin(x/3)+4cos(x/3)的最大值.

问题描述:

函数y=3sin(x/3)+4cos(x/3)的最大值.

y=3sin(x/3)+4cos(x/3)
=5[(3/5)sin(x/3)+(4/5)cos(x/3)]
=5sin(x/3 + α ) (其中cosα=3/5,sinα=4/5)
∈[-5,5]