how high are the poles,in feet?

Question

A cord that is fastened to the top of two poles can be modeled by 1/300x² -x+550, where x and y are measured in feet. The cord touches the ground midway between the poles. How high are the poles, in feet?

Answer 1

This is a question from the Big Ideas textbook series.
https://www.bigideasmath.com/protected/content/dcs_cc2/a1/c08/ct/tp_08_ct.html

I did not understand the question. I found it to be poorly worded. So I searched the internet and found this post.

 

The vertex is (150,475).

 

The fact that suspended cables form catenaries, not parabolas, bothered me from the beginning.

Answer 2

1.

A cord (or wire or cable) hanging by its own weight does not form a parabola (Proved by Jungius in 1669). It forms a catenary. The Gateway Arch in St. Louis is an inverted catenary.

2. 

If a parabola were to "touch the ground" that would be the same as having the vertex on the abscissa. The vertex would be (0, 0).

3.

The vertex of the function given is (150, 425).

4.

The height of the poles would increase the father they were positioned from the vertex, if a vertex existed. This measure is not given. The height of the poles cannot be determined.

5.

Before posting a question, be sure that the information is accurate.