Hello, ling_c_0202!

A vertex of a square of side is at the origin.

The inclination of one of its sides is .

Find the equations of the sides of the square.

First of all, there are **two** possible squares . . . I'll pick one of them. Code:

| C a sinθ
| o - - - +
| * * :
D * | * :
o | * : a cosθ
:* | * θ :
: * | * :
: * | * :
: θ * | *:
a cosθ : * | o B
: * | * :
: *| * θ : a sinθ
- - + - - - o - - - - - - - - + - - -
a sinθ A a cosθ

Vertex

Vertex

Vertex

Vertex

I'll let __you__ write the equations of the lines . . .