Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**scientia****Member**- Registered: 2009-11-13
- Posts: 224

Inspired by http://www.mathisfunforum.com/viewtopic.php?id=18730.

**Q1 (easy):** How many times in a 12-hour period do the hour and minute hands point in opposite directions?

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,362

Hi;

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**scientia****Member**- Registered: 2009-11-13
- Posts: 224

**Q2 (trickier):** Let *θ* be an arbitrary angle greater than 0° and smaller than 180°. How many times in a 12-hour period do the two hands of a clock make an angle of *θ* between themselves?

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,362

Hi scientia;

I will work on that one as soon as I get done with the easy stuff first.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**scientia****Member**- Registered: 2009-11-13
- Posts: 224

Take your time.

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,362

Hi;

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**scientia****Member**- Registered: 2009-11-13
- Posts: 224

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 106,362

Hi;

Happy New Year!

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

Offline

**OzMark****Member**- Registered: 2013-06-10
- Posts: 9

Q1, refer also also

http://www.mathsisfun.com/puzzles/a-que … -time.html

The question asks for the distance from the bottom of the clock face at 6 o'clock to the tip of the clock hands, what they mean is when do both the hands make an angle to a vertical line on the clock face through 6 o'clock.

The answers for when the hands are at either side of the clock face are ;

12:55 and 23sec, 1:50 46s, 2:46 9s, 3:41 32s, 4:36 55s, 5:32 18s, 6:27 42s, 7:23 5s, 8:18 28s, 9:13 51 s, 10:09 14s & 11:04 37s

There are 11 more solutions when the minute and hour hand are directly on top of each other ;

12:00 00s, 1:05 27s, 2:10 55s, 3:16 22s, 4:21 49s, 5:27 16s, 6:32 44s, 7:38 11s, 8:43 38s, 9:49 5s & 10:54 33s

Also we need to assume the length of the minute and hour hands is the same, or else we cant solve the question at all.

The solution given only cites one of these solutions 8:18 28s, I suppose that is made with reference to the picture.

I can make an explanation of the equations I used if I get a reply to this post, I wasnt going to be bothered if noone reads these.

Have Fun !

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,705

hi OzMark

Welcome to the forum.

I've not tried this puzzle but it looks like you've discovered a bug; maybe the wording should be changed ... perhaps indicating that equal angles are wanted rather than distances. I'll raise it with the page creator, MathsIsFun, himself.

Hope you enjoy your membership. Looking forward to your contributions.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

Pages: **1**