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easy math question

toph99

Diamond Member
i seem to have misplaced my procedure for finding the shortest distance from a point to a line, and i need it to finish my work. anyone here know what it is? here's a sample question:

find the exact value of the shortest distance from the given line to the given point.

(0,0) and y=2x-10

thanks 🙂

/me keeps looking for his note
 
You can use the distance formula sqrt[(x2-x1)^2 + (y2-y1)^2], then take the derivative of that equation and set it equal to zero to find the minimum of the distance.

Or, probably simpler, you can find the equation for the line that is perpendicular to your line that also goes through (0,0)
 
Do you know how to find the equation of a line perpendicular to a given line? If so, find that equation, & then adjust it accordingly to run it through your given point.

Viper GTS
 
ah! now i remember! 🙂 thanks guys. it was the perpendicular of the line which goes through 0,0. thanks 🙂

/me scratches head
how do i find out where the perpendiculat going to (0,0) intersects the other line?
 
slope = -1/2

y=mx+b, b=0 since the line goes through (0,0)

y=-1/2x

which crosses your line at (4,-2)
 
Given a Line A*x+B*y+C=0 and any given point (x1, y1)
the distance between the point and the line is given by the following equation:

Distance = abs[A*x1+B*y1+C] / (A^2+B^2)^.5
 
yep use that distance between a line and a point equation to solve this problem

anyway, you shouldnt be asking such simple question in here 🙂
 
i found my note 🙂
btw this is grade 10 math so i should hope everyone in here would know it 😛 my dad took a half hour figuring it all out using the Pythagorean Theorum, lol. thanks guys 🙂
 
btw this is grade 10 math so i should hope everyone in here would know it

It may sound dumb, but I don't remember a lot of the stuff that I did in algebra & trig. I could figure most of them out, if I wanted, but all the formulas for finding crap like that...

I don't remember half of it.

Viper GTS
 


<< I don't remember a lot of the stuff that I did in algebra &amp; trig >>



i give myself a month before i completely forget how to do this again 😛 math isn't my thing. now if these were formulas for chemistry or physics, i'd remember them easily 😕
ah well, i just hope i can remember it long enough for the exam in june :Q

thanks guys 🙂
 
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