# altitude equation

• Jul 10th 2008, 11:40 PM
euclid2
altitude 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
• Jul 11th 2008, 12:11 AM
nikhil
Slope of point P is 4/11.
Points do not have slopes.
Is it slope of altitude?
• Jul 11th 2008, 12:14 AM
euclid2
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 11th 2008, 12:30 AM
nikhil
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 11th 2008, 12:38 AM
euclid2
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 11th 2008, 12:48 AM
nikhil
Quote:

Originally Posted by euclid2
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

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 11th 2008, 12:53 AM
euclid2
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, 01:05 AM
nikhil
Quote:

Originally Posted by euclid2
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

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.