cos(x+π/4)=1/2,x属于(0,2π),求x解集

Question

cos(x+π/4)=1/2,x属于(0,2π),求x解集

Answer 1

因为cos(x+π/4)=1/2,
所以x+π/4=2kπ+π/3 或 x+π/4=2kπ+5π/3
解得x=2kπ+π/12 或 x=2kπ+17π/12
因为x属于(0,2π),所以k取0
得x=π/12 或 x=17π/12