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Area of Shapes. The area of a shape is the space it occupies. Write down the name of each shape. A powerpoint presentation by Carmelo Ellul Head of Department (Mathematics). Parallelogram. Trapezium. Square. Rectangle. Circle. Triangle. Area of Shapes. Click button to select topic.
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Area of Shapes • The area of a shape is the space it occupies. • Write down the name of each shape. A powerpoint presentation by Carmelo Ellul Head of Department (Mathematics) Parallelogram Trapezium Square Rectangle Circle Triangle
Area of Shapes • Click button to select topic. Square Rectangle Parallelogram Triangle Trapezium Circle End Show
The Square Area = lxb e.g.Find the area of a square of side 3.5 cm. Discuss and work out this example together with your friend. b breadth A = l x b A = 3.5 cmx 3.5 cm = 12.25 cm2 l length
The Rectangle Area = lxb 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 xb A = 3.5 cmx 8 cm = 28 cm2 b l
3.8 cm 10.3 cm h b The Parallellogram Area = bxh e.g.Find the area of a parallelogram correct to 1 d.p. height h base b A = b xh A = 10.3 cmx 3.8 cm = 39.14 cm2 = 39.1 cm2 Discuss and work out this example together.
A 4 cm B C 11.7 cm h h h b b b Area of = ½b h Area of parallelogram = b h Area of = ½ area of parallelogram The Triangle e.g.Find the area of triangle ABC correct to the nearest cm2. Area = ½b h h height b base A = ½b xh A = ½ x 4 cmx 11.7 cm = 23.4 cm2 = 23 cm2 Discuss and work out this example together.
8.5 cm 6 cm 12 cm Rotate the trapezium The Trapezium e.g.Find the area of the trapezium. Area = ½h(a + b) Length of side a a h height Length of side b b h = 6cm, a = 8.5 cm, b = 12 cm A = ½h(a + b) A = ½x 6 cm x (8.5 cm + 12 cm) = ½x 6 cm x 20.5 cm = 61.5 cm2 Decide about the values of a, b and h to find the area. b a h a b Area of 1 trapezium is half h(a + b) Area of trapezium = ½h(a + b) Area of parallelogram = h(a + b) The 2 trapeziums form a parallelogram Copy the trapezium
The Circle Area = pr2 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 = p r2 = px9.5 cm x9.5 cm = 283.5 cm2 = 284 cm2 Radius Find the radius first and then work out this example together. r Centre Remember: the radius of a circle is half the diameter.
The Circle Area = pr2 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 = p r2 = px 9.5 cm x9.5 cm = 283.5 cm2 = 284 cm2 r Remember: the radius of a circle is half the diameter. End Show