# math

posted by on .

If the vertices of quadrilateral ABCD are A(1,1), B(-2,3), C(-4,-1), and D(2,-3), and the quadrilateral is dilated so that it's perimeter is 2 times the original perimeter, what would the vertex matrix look like?

• math - ,

1. What form does your dilation take?

you could keep one point in its present position and simply double the length of each side.
e.g. keep B(-2,3) but move A to A1(4,-1) so that A becomes the midpoint of BA1.
I would be relatively easy to work your way around in the same way for the other sides.
Of course you could do this again by keeping point A constant, etc.

Another way would be to find the intersection of the two diagonals, call it F, and then joining F to the original vertices and extending FA,FB,FC,and FD its own length.

2. Some of this can be done with vector geometry, but do you know how to work with vectors?

3. I am not sure what you mean by a "vertex matrix".

4. What course level is this? Is it simply analytical geometry?

• math - ,

1. not sure
2. Don't remember but the book says to do it with matrices.
3. My book says a vertex matrix is a matrix into which the coordinates of a polygon's matrices are placed.
4. Algebra 2 - Transformations with matrices

• math - ,

ok, then keeping B as it is, I found
A1(4,-1)
C1(-6,-5)
D1(6,-9)

each of my new sides are twice as long as the old ones, but the new lines are parallel to the original
e.g. AD is parallel to A1D1

• math - ,

Yes, but how would I represent this in a matrix?