函数f(x)=cos(x+π)(x∈【π/12,5π/6】)的值域为多少?

Question

函数f(x)=cos(x+π)(x∈【π/12,5π/6】)的值域为多少?

Answer 1

x∈[π/12,5π/6]
x+π∈[π/12+π,5π/6+π]
－cos5π/6≤f(x)=cos(x+π)≤-cosπ/12