# Optimization Train Problem

Delber

## Homework Statement

A train leaves the station at 10:00 and travels due south at a speed of 60 km/h. Another train has been heading due west at 45 km/h and reaches the same station at 11:00. At what time were the two trains closest together?

## Homework Equations

$$c^{2}=a^{2}+b^{2}$$

## The Attempt at a Solution

The trouble I am having is the wording of the question. I think it means the trains left from two different stations and will arrive at the same time together at one station. So the equation for that scenario is:

$$f(t) = \sqrt{(60-60t)^{2}+(45t)^{2}}$$

However I get a range outside the limit of one hour. I think I'm just confused about he wording if someone can clarify it for me. Any help is appreciated.

Homework Helper

## Homework Statement

A train leaves the station at 10:00 and travels due south at a speed of 60 km/h. Another train has been heading due west at 45 km/h and reaches the same station at 11:00. At what time were the two trains closest together?

Hi Delber! It means train 2 arrives at the same station one hour after train 1 left. Delber
Thanks for the clarification.

So the new equation should be:

$$f(t)=\sqrt{(45-45t)^{2}+(60t)^{2}}$$?

Edit: Yep, I get the correct answer in the book. Thanks for the help.

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