2. Area of Shapes n The area of a shape is the space it occupies. n Write down the name of each shape. Square Rectangle ParallelogramTrapezium Circle Triangle A powerpoint presentation by Carmelo Ellul Head of Department (Mathematics)

3. Area of Shapes n Click button to select topic. Square Rectangle Parallelogram Trapezium Triangle Circle End Show

4. The Square Area = l x b b e.g. Find the area of a square of side 3.5 cm. Discuss and work out this example together with your friend. A = l x b A = 3.5 cm x 3.5 cm = 12.25 cm 2 llength breadth

5. The Rectangle Area = l x b l b e.g. Find the area of a rectangle of length 3.5 cm and height 80 mm. Discuss and work out this example together. Since units must be the same: 10 mm = 1 cm 80 mm = 80 mm ÷ 10 = 8 cm A = l x b A = 3.5 cm x 8 cm = 28 cm 2

6. The Parallellogram Area = b x h baseb heighth b h e.g. Find the area of a parallelogram correct to 1 d.p. 3.8 cm 10.3 cm Discuss and work out this example together. A = b x h A = 10.3 cm x 3.8 cm = 39.14 cm 2 = 39.1 cm 2

7. The Triangle Area = ½ b  h e.g. Find the area of triangle ABC correct to the nearest cm 2. Discuss and work out this example together. A = ½b x h A = ½ x 4 cm x 11.7 cm = 23.4 cm 2 = 23 cm 2 baseb heighth Area of parallelogram = b  h b h Area of = ½ area of parallelogram b h 11.7 cm 4 cm A BC Area of = ½b  h b h

8. b  Area of trapezium = ½ h(a + b) Rotate the trapezium The 2 trapeziums form a parallelogram Area of parallelogram = h(a + b) Area of 1 trapezium is half h(a + b) Area = ½h(a + b) a b h h a e.g. Find the area of the trapezium. 12 cm 8.5 cm 6 cm Decide about the values of a, b and h to find the area. h = 6cm, a = 8.5 cm, b = 12 cm A = ½h(a + b) A = ½ x 6 cm x (8.5 cm + 12 cm) = ½ x 6 cm x 20.5 cm = 61.5 cm 2 The Trapezium Length of side a Length of side b Copy the trapezium a b height

9. The Circle Area =  r 2 Centre Radius r Remember: the radius of a circle is half the diameter. e.g. The diameter of a circle is 19 cm. Find, correct to nearest whole number, the area of a circle. Find the radius first and then work out this example together. r = 19 cm ÷ 2 = 9.5 cm. A =  r 2 =  x 9.5 cm x 9.5 cm = 283.5 cm 2 = 284 cm 2

10. The Circle Area =  r 2 r Remember: the radius of a circle is half the diameter. e.g. The diameter of a circle is 19 cm. Find, correct to nearest whole number, the area of a circle. r = 19 cm ÷ 2 = 9.5 cm. A =  r 2 =  x 9.5 cm x 9.5 cm = 283.5 cm 2 = 284 cm 2 End Show