P 2 = 1。

That is, x 2+y 2 = 1

Then the point set of p= 1 forms a circle with (0,0) as the center and 1 as the radius.

Because θ = 45.

Therefore, x = PCOS θ = PSIN θ = Y.

That is to say, the horizontal and vertical coordinates of the point (x, y) are equal.

Therefore, the point set θ=π/4 is the straight line y=x in the plane rectangular coordinate system.