Photo:
THE MIRROR
This week's puzzle is not particularly difficult.
That's why you only get one minute to solve it.
Without a piece of paper and without a pen.
Can you do it?
A quadrant is given.
A yellow rectangle is drawn in it.
In addition, there are two length specifications - see drawing above.
How long is the red line?
The line has
a length of 12
.
You don't need to use the Pythagorean theorem or perform a complicated calculation to find out.
It suffices to realize that the second diagonal of the yellow rectangle is exactly the radius of the quadrant and has a length of 7 + 5 = 12.
Because the two diagonals of a rectangle are equal, 12 is also the length of the red line.
I discovered this geometry puzzle in the book "My Best Mathematical and Logic Puzzles" by Martin Gardner.
In case you missed a mystery from the past few weeks, here are the most recent episodes:
Does a cube fit through itself?
The monster number and its two non-divisors
sink squares
Good luck and bad luck in the raffle
heirs in the square
The super heavy freight train
Magic with prime numbers
Strict logic in the rabbit hutch
You shall be many friends
Which number comes next?