1. Area of a Right Angled Triangle

2. How can we work it out?
Draw a right angled triangle on squared paper (10 cm high, 15 cm wide)
Make it into a rectangle. Cut out the two triangles. Are they identical?
What is the area of one of the triangles?
15cm
5cm

3. The formula (or rule)
The area of a right-angled triangle is the base x height ÷ 2
Example:- Find the area
Base = 5cm
Height = 4cm
Base x Height ÷ 2
= 5 x 4 ÷ 2 = 10cm
4cm 2
5cm

4. Compound Shapes How can we work out the area of this? Step 1 Step 2
Split up into a triangle
and rectangle
2cm
4cm
5cm
Step 2
Work out the missing lengths
3cm
3 x 4 =12
Step 3
Work out the area of the shapes
separately
4cm
4 x 2 ÷ 2
= 4
Step 4
Add the two areas together
Total area =
= 16 cm 2