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Mathematics 16 Online
OpenStudy (anonymous):

Attached. Don't just give me an answer, I need to know how to do this.

OpenStudy (anonymous):

OpenStudy (anonymous):

Just like the midpoint formula finds the average of the two points, these are like weighted averages.

OpenStudy (anonymous):

i.e. to find the point one-third the way from K to M, you'll be finding the average of 3 things, but 2 of those things will be point K (to weight the average towards K. So, multiply the coordinates of K by 2, then add the coordinates of M; finally, divide by 3. To get one-third from M to K, do the same thing, but double M's coordinates instead to weight the average in favor of M.

OpenStudy (phi):

which question?

OpenStudy (anonymous):

Let's start with the first one.

OpenStudy (phi):

do you know about congruent triangles? |dw:1350515470254:dw| the hypotenuses are all equal (that is what the problem asks for) the angles are all equal. so all 3 triangles are congruent (by angle side angle) that tells you the x's are all the same and the x's add up to the total x difference between the two points. same for the y's for each triangle. does that help?

OpenStudy (anonymous):

A little. I'm just not sure how to continue from there.

OpenStudy (phi):

step 1: I would find the total x distance between the 2 points. ditto for the y difference.

OpenStudy (phi):

I assume you can do that?

OpenStudy (anonymous):

Yes.

OpenStudy (anonymous):

5 = x 3 = y

OpenStudy (phi):

based on each triangle has the same x value, what x value does each have?

OpenStudy (anonymous):

5/3 ?

OpenStudy (phi):

yes because you know 5/3+5/3+5/3 must add up to 5 and each triangle has y=1 if you start at (-2,1) where is the next point they are asking for?

OpenStudy (anonymous):

( -1/3, 2)

OpenStudy (phi):

and the 2nd point they want?

OpenStudy (anonymous):

(4/3, 3)

OpenStudy (phi):

so that is the answer

OpenStudy (phi):

notice if we add (5/3,1) to the 2nd point we end up at (3,4) which is point M. it all works out.

OpenStudy (phi):

can you do question 2. It is the same idea, except you go 3/5 of the way from A to B instead of 1/3 (or 2/3) of the way.

OpenStudy (anonymous):

Yeah, I think so.

OpenStudy (anonymous):

Here's the weighted average method I was talking about: The points are K(-2,1) and M(3,4). To find a point one-third the way from K, we weight the average towards that point. First double K -> 2K(-4,1) and add it to M 2K+M= (-1,6). Divide by 3 -> (-1/3,2) For two-thirds from K, double M and add it to K: K+2M = (4,9) Divide by 3 -> (4/3,3) The tri-points are (-1/3,2) and (4/3,3). This method can be generalized into formula that works for dividing any segment into any number of parts.

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