A triangle is a closed shape with three sides and three vertices. The general formula to calculate the area of a triangle is half of the product of its base and height.

TRIANGLE: Now he's 4 cm high and 3 cm wide, like me. He's 12 square cm, so I must be half that… 6 square centimetres! And whatever shape I am it still works! RECTANGLE: You're just really embarrassing ...

WHAT YOU NEED: two pieces of paper/card, pencil, scissors, ruler. Image caption, STEP 1: Place one piece of card on top of the other and use the ruler to draw a line from the bottom left corner of the ...