[In a diagram, six equilateral triangles form a zigzag shape that resembles two trapeziums with half their longest sides touching. The narrator reads out the onscreen text.]

NARRATOR: Question three. This shape is made with six equilateral triangles. What is the perimeter of the shape - 6 centimetres, 8 centimetres, 10 centimetres or 18 centimetres? Each triangle is equilateral, so each side of each triangle is 1 centimetre long. The perimeter of the shape is made up of one, two, three, four, five, six, seven, eight sides of an equilateral triangle. So 8 times 1 centimetre gives a total perimeter of 8 centimetres.