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### Clock Hands

```
Date: 01/14/98 at 02:00:55
From: kim
Subject: Clock hands

The minute hand of a clock is 3 cm longer then the hour hand. If the
distance between the tips of the hands at nine o'clock is 15 cm, how
long is the minute hand?
```

```
Date: 01/15/98 at 09:22:16
From: Doctor Joe
Subject: Re: Clock hands

Dear Kim,

Let the length of the minute hand be x cm.
Then the length of the hour end hand is (x-3) cm.

When we look at the position of the hands at 9 o'clock, we see that
the two hands are at right angles:

12

|
|
|
|
|
9      ________|

The next thing you should do is to find the distance between the tips
at this position.  (Hint: use the famous Pythagoras Theorem.)

Then form a quadratic equation in x.

If you have any further difficulties solving this question, please
feel free to ask again. I don't want to rob you of all the fun of
solving this problem.

-Doctor Joe,  The Math Forum
Check out our web site!  http://mathforum.org/dr.math/
```
Associated Topics:
Middle School Word Problems

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