Find the area of the triangle formed by the lines `y-x=0,x+y=0`and `x-k=0`.

Explanation

To find the area of the triangle formed by the lines \( y - x = 0 \), \( x + y = 0 \), and \( x - k = 0 \), we can follow these steps:

### Step 1: Identify the equations of the lines
The equations given are:
1. \( y - x = 0 \) which simplifies to \( y = x \)
2. \( x + y = 0 \) which simplifies to \( y = -x \)
3. \( x - k = 0 \) which simplifies to \( x = k \)

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