

Let the equation of straight line is:
y = mx + c ..........1
Since it passes through (0,0)
then
0 = 0*x + c
=> c = 0
From eqaution 1, we get
y = mx ..........2
Again given that line makes equal angle with co-ordinate axes
So slope = m = tan45
=> m = 1
From eqution2, we get
y = m
This is the required equation of line.
