March 7,2012

Aim: How do we find compound loci ?

A compound loci is a problem that involves finding the locus but it also involves the words "AND" and "And ALSO".

Exercise :

Try figure out, if the statements below are compound loci or only locus problems.

1) What is the locus of points 3 inches from point B?

2) Graph the locus of points equidistant from x=7 and y=3?

3) Im hungry ....

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In compound loci problems there are certain steps to take:

Problem 1:

Parallel lines r and s are 8 meters apart, and A is a point on line s.  How many points are equidistant from r and s and also 4 meters from A? 

First step :

Break down the first line of the problem and sketch it 

Parallel lines R and S are 8 meters apart, and A is a point on line S.

Second step :

re-read the second sentence before the AND.

 How many points are equidistant from R and S. 

According to the Locus theorem if we need to find locus of two parallel lines like R and S then the locus would form a line.

Then sketch it 

Third step :

re-read the end of the sentence.

Also four meters from point A. 

Then sketch it.

Finally in the compound loci you see where both the equidistant line and the circle of point A touches. In this case its one time so the answer is 1.

Try it :D

Two points A and B are 7 units apart.  How many points are there that are 12 units from A and also 4 inches from B?

Choose:  0  1 2 3

Sources used :

for both problems: regentsprep.org

the picture with the question mark :http://www.brainbasedbusiness.com

the rest is in my notes and head :P