Distance from a point to a line

Use the distance from a point to a line formula to check the distance from P(7, -4) to 3x - y =5

okay the slope of the line is -3/1, which is perpendicular to 1/3

so the equation i think is y+4/x-7

which ive then written 3(y+4)=1(x-7)

then 3y+12 = x-7

and i wrote x +3y = 19,

i'm not sure if what i just wrote was correct, and i don't know where to go from there..

Re: Distance from a point to a line

Well for starters, your line is , which becomes , and so its gradient is 3, not -3. Therefore the perpendicular line should have gradient .

Re: Distance from a point to a line

There is a formula for the distance between the line ax+by+c=0 to the point (x_{1},y_{1})

It is

Before applying the formula make sure the equation of the line is in that form exactly.

Re: Distance from a point to a line

Quote:

Originally Posted by

**Shakarri** There is a formula for the distance between the line ax+by+c=0 to the point (x

_{1},y

_{1})

It is

Before applying the formula make sure the equation of the line is in that form exactly.

It still makes me smile seeing your signature :)