BBC

How to show the area of a parallelogram is base × height

WHAT YOU NEED: ruler, scissors, pencil, piece of card. Image caption, STEP 1: Use the ruler and pencil to draw a diagonal line from the bottom left corner of the card to any point on the top edge of ...
BBC

How to show the area of a triangle is ½ × base × height

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 ...