# 10 most difficult geometry riddles

A list of ten (out of 20) geometry related questions that are the most often answered incorrectly

Geometry quiz
## How is the infinity symbol called?

Lemniscate refers not only to the infinity symbol but also to any geometric shape that is curved like a figure-eight.

very hard

17%

lemniscate

lemniscate

17%

omniscate

omniscate

61%

perniscate

perniscate

11%

ettoniscate

ettoniscate

8%

Created by: Ninjai.
Statistics based on 475 answers in 3 languages
»

## The illustration shows the figure known in mathematics as;

Lune of Hippocrates,. In geometry, the lune of Hippocrates, named after Hippocrates of Chios, is a lune bounded by arcs of two circles, the smaller of which has as its diameter a chord spanning a right angle on the larger circle. Equivalently, it is a non-convex plane region bounded by one 180-degree circular arc and one 90-degree circular arc. It is the first curved figure to have its exact area calculated mathematically.

very hard

24%

Tales' sails

Tales' sails

25%

Pythagorean sickles

Pythagorean sickles

23%

Archimedes' arches

Archimedes' arches

25%

lune of Hippocrates,

lune of Hippocrates,

24%

Created by: Tschuka .
Statistics based on 243 answers in 2 languages
»

## In which year did Leonhard Euler introduced the symbol "i" to represent the square root of -1 ?

In 1777. The letter "i" as a designation of the element from -1 was proposed by Leonhard Euler in 1777. Later, from 1801, this designation was popularized by Carl Friedrich Gauss. Currently, it is the most commonly used symbol of the imaginary unit.

hard

41%

in 1555

in 1555

8%

in 1666

in 1666

25%

in 1777

in 1777

41%

in 1888

in 1888

25%

Created by: Tschuka .
Statistics based on 2174 answers in 2 languages
»

## 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

42%

10,002 km

10,002 km

9%

20,004 km

20,004 km

42%

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 16212 answers in 2 languages
»

## Which quadric surface is shaped like a saddle?

Hyperbolic paraboloid. The widely sold fried snack food Pringles potato chips resemble a truncated hyperbolic paraboloid. The distinctive shape of these chips allows them to be stacked in sturdy tubular containers, fulfilling a design goal that they break less easily than other types of chip.

hard

43%

parabolic cylinder

parabolic cylinder

8%

elliptic paraboloid

elliptic paraboloid

27%

hyperbolic paraboloid

hyperbolic paraboloid

43%

elliptic hyperboloid

elliptic hyperboloid

19%

Created by: Ninjai.
Statistics based on 1375 answers in 3 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 29994 answers in 2 languages
»

## What is the approximate value of the golden ratio ("phi")?

1.61. In mathematics, two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. It is often used for aesthetics in art and design.

hard

47%

3.14

3.14

18%

2.16

2.16

25%

1.61

1.61

47%

0.87

0.87

8%

Created by: Ninjai.
Statistics based on 6092 answers in 2 languages
»

## The geometrical structure depicted in the picture is called ...

Spiral of Theodorus. In geometry, the spiral of Theodorus is a spiral composed of contiguous right triangles. It was first constructed by Theodorus of Cyrene.The principle of construction is based on the Pythagorean theorem.

hard

49%

Hippocrates hairpin

Hippocrates hairpin

8%

Spiral of Archimedes

Spiral of Archimedes

27%

Euclid's crust

Euclid's crust

14%

Spiral of Theodorus

Spiral of Theodorus

49%

Created by: Tschuka .
Statistics based on 602 answers in 2 languages
»

## A triangle can NOT have sides of ...

1cm, 2cm, 3cm. The triangle inequality states that the sum of the lengths of any two sides of a triangle must be greater than or equal to the length of the third side

hard

55%

1cm, 2cm, 3cm

1cm, 2cm, 3cm

55%

4cm, 5cm, 6cm

4cm, 5cm, 6cm

6%

7cm, 8cm, 9cm

7cm, 8cm, 9cm

6%

All of the answers are correct

All of the answers are correct

30%

Created by: lukasz Poland.
Statistics based on 2163 answers in 2 languages
»

Play geometry quiz and see all the questions.