Haikou cos photography

Point p (sin α-cos α, tanα) is in the first quadrant,

So sin α-cos α >: 0, tan α >: 0,

From tan α >: 0, we can know that α is in the first or third quadrant.

When α is in the first quadrant, sin α >; 0，cosα& gt； 0,

Through sin α-cos α >; 0:sinα& gt； cosα& gt； 0,

Then tan α >; 1, α is within [0,2π],

So α∈(π/4, π/2).

When α is in the third quadrant, sin α

Through sin α-cos α >; 0:0 & gt； sinα& gt； cosα，

Then tan α

So α ∈ (π, 5π/4).

To sum up, α∈(π/4, π/2)∩(π, 5π/4).