Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
8. Coordinate Proofs
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Exercise 23 Page 288

Given a length of 3h, a width of k, and a vertex at (- h,k) the length has to be parallel to the x-axis and the width has to be parallel to the y-axis.

A

Practice makes perfect

Let's plot the vertex (- h,k) in a coordinate system. We will assume that h and k are both positive numbers which places the point in the second quadrant.

Next, we will draw the length of the rectangle. Since the length is 3 h, and - h is the x-coordinate in (- h,k), we can only draw the length parallel to the x-axis. Therefore, our second vertex will also have a y-coordinate of k. As for the x-coordinate, we can draw the rectangles length both in the negative direction and in the positive direction of the x-axis. Therefore, we end up with two possibilities:

Negative direction:& - h-2h=- 4h Positive direction:& - h+2h=2h Let's add this to our diagram.

Next, we have to draw the width. Because a rectangle has four right angles, the width has to be drawn parallel to the y-axis. Again, there are two options, either we draw the width in the positive direction or we draw it in the negative direction of the y-axis. Negative direction:& k-k=0 Positive direction:& k+k=2k We end up with four possible rectangles. The labeled vertices below are the only possibilities.

The only option that is not represented in the diagram is (h,k) which is option A.