Watch: Calculating the area of triangles
TRIANGLE: I'm a triangle! Of course I am, obviously, you knew that. I've got 3 sides. And this is rectangle.
You're supposed to say hello rectangle…
RECTANGLE: Hi.
TRIANGLE: Now you may well be asking yourself how do we find the area of triangle? Well it's simple really, because there are always 2 of me in rectangle. Look…
RECTANGLE: Ow, get off…
TRIANGLE: So you find the area of rectangle, and then divide it by 2, and that's my area. And it works no matter what size and shape I am. Look… now I'm 4 cm high and 3 cm wide! If rectangle changes shape too…
RECTANGLE: I don't want to.
TRIANGLE: You have to! That's the whole point!
RECTANGLE: It's embarrassing.
TRIANGLE: Go on!
RECTANGLE: Unnh
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. I want to go home.
How do you calculate the area of a triangle?
To calculate the area of a triangle, multiply the height by the width (this is also known as the 'base') then divide by 2.
Can you find the area of a triangle where height = 5 cm and width = 8 cm?
5 × 8 = 40 ÷ 2 = 20
The area is 20cm².
Activity 1
Activity 2
Play Guardians: Defenders of Mathematica to get ready for SATs. game
In this game, use the times tables and more maths skills to defeat monsters and reclaim the Kingdom.
More on 2d shapes
Find out more by working through a topic
- count7 of 10
- count8 of 10
- count9 of 10
- count10 of 10
