Q 01/05

The interior angles of any triangle add up to how many degrees?

A) 180

B) 270

C) 360

D) 540

Answer · why

A) 180

That is why a triangle can have at most one right angle or one obtuse angle: the other two must share what is left.

Q 02/05

A triangle with all three sides the same length is called what?

A) Isosceles

B) Scalene

C) Obtuse

D) Equilateral

Answer · why

D) Equilateral

You see one every day: the yield sign at a road junction is one of these.

Q 03/05

A triangle with all sides of different lengths is called what?

A) Acute

B) Isosceles

C) Equilateral

D) Scalene

Answer · why

D) Scalene

A triangle with exactly two equal sides is isosceles, which is the shape of most gables and pediments.

Q 04/05

What is the name for the longest side of a right-angled triangle?

A) Apothem

B) Chord

C) Altitude

D) Hypotenuse

Answer · why

D) Hypotenuse

The word comes from Greek for 'stretching under', because it stretches beneath the right angle.

Q 05/05

How many degrees are in a right angle?

A) 30

B) 45

C) 60

D) 90

Answer · why

D) 90

The word 'right' comes from the Latin rectus, meaning upright, describing a vertical line meeting a horizontal base.