# 10 most difficult geometry riddles

A list of geometry related questions that are most often answered incorrectly

Mathematics quiz
## What is the maximum distance a plane can fly travelling constantly North?

20,004 km. Continous travel North must eventually end at the North Pole. So, the maximum distance is half of the Earth's meridional circumference, which can be reached if a plane starts at the South Pole.

hard

41%

10,002 km

10,002 km

9%

20,004 km

20,004 km

41%

40,007 km

40,007 km

17%

It can fly endlessly (as long it can)

It can fly endlessly (as long it can)

31%

Created by: globalquiz.org.
Statistics based on 15369 answers in 2 languages
»

## If Earth's radius was larger by 1 meter, how much longer would its equator be?

By approx 6 meters. For each circle, the length of the circumference is c=2πr. Hence, if a radius grows by 1 meter, the circumference grows by 2 π meters - no matter what the initial value of radius was.

hard

45%

by approx 6 meters

by approx 6 meters

45%

by approx 6 kilometers

by approx 6 kilometers

17%

by approx 60 kilometers

by approx 60 kilometers

20%

by approx 6000 kilometers

by approx 6000 kilometers

15%

Created by: SpikeMe.
Statistics based on 28068 answers in 2 languages
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## What line segment can not build triangle?

Line segment lenght: 1cm, 2cm, 3cm. Triangle is build of three line segment. To can build triangle the longest line segment must be a shorter from total two other, so: 1cm+2cm=3cm. Longest line segment (lenght 3cm) isn't shorter from total two other.

hard

53%

Line segment lenght: 1cm, 2cm, 3cm

Line segment lenght: 1cm, 2cm, 3cm

53%

Line segment lenght: 4cm, 5cm, 6cm

Line segment lenght: 4cm, 5cm, 6cm

6%

Line segment lenght: 7cm, 8cm, 9cm

Line segment lenght: 7cm, 8cm, 9cm

7%

All of the answers are correct

All of the answers are correct

32%

Created by: lukasz Poland.
Statistics based on 1366 answers in 2 languages
»

## What is the volume of a soap bubble with radius R=1 cm?

4/3π cm3. Equation for the volume of a sphere: 4/3πR^3.

hard

58%

3/4π cm3

3/4π cm3

19%

4/3π cm3

4/3π cm3

58%

4,3π cm3

4,3π cm3

9%

It isn't possible to calculate

It isn't possible to calculate

12%

Created by: Paweł Kołodziejczyk.
Statistics based on 14463 answers in 2 languages
»

## Which shape is larger?

None of them. Both shapes are the same, but the bottom one is placed more to the right. This is however difficult to notice. It is known as Jastrow Illusion.

average

66%

A

A

2%

B

B

17%

None of them

None of them

66%

Both are larger

Both are larger

12%

Created by: globalquiz.org.
Statistics based on 33749 answers in 4 languages
»

## Which direction is not possible to point at when standing at the South Pole?

Neither east, west, nor south. At the South Pole every direction is north.

average

66%

east

east

2%

west

west

2%

north

north

27%

neither east, west, nor south

neither east, west, nor south

66%

Created by: globalquiz.org.
Statistics based on 17985 answers in 2 languages
»

## Which lines are parallel?

Green, blue and red. This is a well known Zöllner illusion, first described in 1860. It may be caused by this impression of depth. The black lines are parallel, too!

easy

70%

blue and red only

blue and red only

4%

green and red only

green and red only

8%

green, blue and red

green, blue and red

70%

none

none

16%

Created by: globalquiz.org.
Statistics based on 20957 answers in 2 languages
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## How many edges does a Möbius strip have?

One. The Möbius strip is a surface with only one side and only one boundary component (edge). A line drawn starting from the seam down the middle will meet back at the seam but at the "other side". If continued the line will meet the starting point and will be double the length of the original strip.

easy

72%

one

one

72%

two

two

18%

three

three

4%

four

four

3%

Created by: globalquiz.org.
Statistics based on 16439 answers in 4 languages
»

## How is this polygon called? (the one over the circles)

Square. In this Ehrenstein illusion the sides of a square placed inside a pattern of concentric circles take an apparent curved shape. But in reality, the sides are straight.

easy

74%

square

square

74%

rhomboid

rhomboid

10%

concave square

concave square

8%

concave rhomboid

concave rhomboid

6%

Created by: Debbie Fox.
Statistics based on 36876 answers in 2 languages
»

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