Question

What is the equation of the line passing through `(1,1)` and `(0,0)`?

Answer 1

`y = x`

Explanation:

Consider a point `(x,y)` on the line
`tan theta = (y - 0) / (x - 0) = y / x`
Also `tan theta = (1 - 0) / (1 - 0) = 1`
Equating the two `tan theta`, we get `y / x = 1`
ie `y = x`