Thread: Shrtest distance between fly and spider in a room.

A spider and a fly are in the same room. The spider is hungry and the fly is asleep. The room is 15m long, 6m wide and 6m high. The spider is on an end wall, 0.5m from the ceiling and half way between the side walls. The fly is on the other side wall, 0.5m from the floor and halfway between the side walls. The spider wants to reach the fly but must crawl on the floor, walls and ceiling to get to it. What is the shortest route the spider might take? (HINT: IT IS NOT 21m)

This question was a question a friend recently gave me, to see if I could solve it. I have read and re-read it so many times But anyway, I would just like to know the working out and the answer for this problem!
I think the Pythagoras Theorem is involved somewhere.
Thanks!
I need this problem solved as soon as possible please!

The total horizontal distance it needs to travel is 21 meters.

The total vertical distance it needs to travel is 5 meters.

Now using the pythagorean theorum, can you solve the total distance?

I can understand the 5 metres part, but how did you get 21 metres for the horizontal distance?
I am afraid I still don't understand after that.

So, using Pythagoras' Theorem,
Side 2 (the Distance) = Square Root of (21^2-5^2)
= Square Root of (441-25)
= Square Root of 416
= 20.40

So the spider traveled 20.40 metres to get to the fly.
Is that right?

Actually ignore me. I wasn't thinking. I got the distance to be longer than 21 meters.

Where did you get the hint that it wasn't 21 meters?

My friend told me. She said that there was a shorter distance than 21 metres.
Thanks for your help anyway

That's a "ye olde Dudeney" puzzle:
Pythagorean Theorem or The Spider and the Fly