1)2cosa square +cosa= 1 a=60.

(2) f(x+60)= root 3sin(x+60)+cos60.

= root 3sin(x+60)+ 1/2

According to the monotonic decreasing of sine function, it is concluded that x+π/3 belongs to (2kπ+π/2) to 2kπ+(3π/2).

X belongs to (2kπ+π/6) to (2kπ+7π/6).

It seems so! I hope I can help you!

Sorry, I can't help you.