Brain Teasers
Perfect Decagon?
Trick
Trick brain teasers appear difficult at first, but they have a trick that makes them really easy.Trick
Jo claimed "I can draw a perfect decagon using only a pencil. No ruler, no protractor, no compasses, nothing!"
She did it, even though she had never had any practice with drawing shapes, and she wasn't lucky. How?
She did it, even though she had never had any practice with drawing shapes, and she wasn't lucky. How?
Hint
What is a perfect decagon?Answer
Jo had simply drawn a shape with 10 sides. The teaser never said the decagon had to be regular. "Perfect" only meant fulfilling the requirements of a decagon; to have 10 sides, 10 angles etc.Hide Hint Show Hint Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments
Oh! Tricky!
Woah. I was thinking hand measurements.
Easy Great teaser though!
Without even a straightedge, I might question how straight the hand-drawn lines would actually turn out to be. A decagon only needs 10 sides, but they do need to be line segments, not arcs or squiggles.
However, I did think that she might have found a way to fold and unfold a bunch of creases in the paper (like an origami project) that she could then trace with the pencil to form the sides of the decagon. The answer doesn't suggest this, though.
I think that would count as using the paper as equipment.
Logically there is no perfect decagon
Nice teaster cub.
Thanks Steven!
Wow, I actually guessed it.
No, this is a bad riddle. The sides wouldn't be perfectly straight, so it doesn't work.
good riddle! i dont know about these people saying it cant be perfect because the lines wouldnt be straight but i can draw a straight line without equipment easily
To post a comment, please create an account and sign in.
Follow Braingle!