Given the vertices of a triangle P(3,7), Q(-8,2), R(-4,-9) determine the equation of altitude that passes through the point P.

The slope of P is 4/11, is what I have

Please help

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- Jul 10th 2008, 10:40 PMeuclid2altitude equation
Given the vertices of a triangle P(3,7), Q(-8,2), R(-4,-9) determine the equation of altitude that passes through the point P.

The slope of P is 4/11, is what I have

Please help - Jul 10th 2008, 11:11 PMnikhil
Slope of point P is 4/11.

Points do not have slopes.

Is it slope of altitude? - Jul 10th 2008, 11:14 PMeuclid2
The slope of the line passing through the point is 4/11.

I first calculated the slope of QR, which was -11/4, and p is a perpendicular bisector of that line so it is the negative reciprocal 4/11 which is passing through the point P. - Jul 10th 2008, 11:30 PMnikhil
Ok so what i have understood is that slope of line(altitude) passing throug P whose equation is to be written is 4/11. Did you mean the same?

- Jul 10th 2008, 11:38 PMeuclid2
My understanding is that the slope passing through p is 4/11, yes.

The equation of a line im y=mx+b

If you plug in the co-ordinates for P you will get this

7=4/11(3)+b

i am unable to figure it out from here - Jul 10th 2008, 11:48 PMnikhil
See Equation of any line can be written as y=mx+b.

One should know the value of m and b.you have calculated m=4/11.but still don't know b.

By 7=4/11(3)+b we can get value of b that is

b=7-12/11

now put the value of m and b in y=mx+b and you will get the desired equation.now any problem?Feel free to ask. - Jul 10th 2008, 11:53 PMeuclid2
Ok but now we must make a final product

y=4/11+7-12/11

Is that how the final product is or do we have to simplify 7-12/11 before putting it into the final product, if so how?

Thanks - Jul 11th 2008, 12:05 AMnikhil
No. The final product is

y=4/11 (x)+7-12/11

don't forget 1)x and 2)completing calculation of

7-12/11.

May be you should think about the concepts like how an equation can represent a line,what parameters are needee and why.this will make your understanding very clear.