Section Formula

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Section Formula

by knight247 » Sun Aug 28, 2011 5:04 am
What are the coordinates for the point on Line AB (see figure) that
is three times as far from A as from B, and that is in between points
A and B?

OA is [spoiler](-2.75, 1.5)[/spoiler]

Another Manhattan problem. The solution given by them is a bit long and drawn out. I recognise that this problem can easily be solved using the section formula i.e If a point Z divides a line internally in the ration m:n then the (x,y) co-ordinates of Z are given by the formula
{(m.x2+n.x1)/m+n,(m.y2+n.y1)/m+n)}

In this case (x1,y1)is (-5,6) and (x2,y2) is (-2,0).But when I solve it using the section formula, I get a different answer altogether. Hoping to get some insight. Thanks
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by Frankenstein » Sun Aug 28, 2011 5:40 am
Hi,

You must have done calc. mistake:
m=3,n=1
So, [3(-2)+1(-5)] = -11/4 = -2.75
[3(0)+1(6)]/4 = 1.5
Cheers!

Things are not what they appear to be... nor are they otherwise

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by navami » Mon Aug 29, 2011 12:45 pm