Question

How do you find equations of the lines passing through (1,3 ) perpendicular to line x+y=0?

Answer 1

`y = x + 2`

Explanation:

There will only be one line which meet these conditions.

`x+y = 0 rArr y = -x`
This line has a gradient = -1.
The line perpendicular to it has a gradient of 1.
`" "m_1 xx m_2 = -1`

We have (x,y) = (1,3) and m = 1

`y = mx + c` becomes `3 = 1(1) + c`

`3 = 1 +c rArr c = 2`

Equation is `y = x + 2`