Q 01/05

Whose theorem says the square of a right triangle's hypotenuse equals the sum of the squares of the other sides?

A) Archimedes

B) Pythagoras

C) Euclid

D) Thales

Answer · why

B) Pythagoras

Babylonian clay tablets show the relationship was known a thousand years before Pythagoras was born; he just got the naming rights.

Q 02/05

Pi is the ratio of a circle's circumference to what?

A) Its chord

B) Its radius

C) Its area

D) Its diameter

Answer · why

D) Its diameter

Pi is the ratio of a circle's circumference to its diameter, about 3.14159, so every circumference is just over three times the diameter.

Q 03/05

What do the interior angles of any triangle add up to?

A) 360 degrees

B) 180 degrees

C) 90 degrees

D) 270 degrees

Answer · why

B) 180 degrees

The interior angles of any flat triangle sum to 180 degrees, a result proved in Euclid's Elements (Book I, Proposition 32) around 300 BC.

Q 04/05

What is the only even prime number?

A) 7

B) 5

C) 2

D) 3

Answer · why

C) 2

Every other even number is divisible by 2, so it has a factor besides itself and 1 and cannot be prime.

Q 05/05

In the quadratic formula, the expression b² − 4ac is called what?

A) The determinant

B) The coefficient

C) The derivative

D) The discriminant

Answer · why

D) The discriminant

The discriminant b² − 4ac tells how many real roots a quadratic has: negative means none, zero means one repeated root, positive means two.