We are Learning to Calculate Area of Composite

Area of shapes made from rectangles How can we find the area of this

Area of shapes made from rectangles How can we find the area of the

Area of an irregular shape on a pegboard How can we find the area

Area of an irregular shapes on a pegboard How can we find the area

Area formulae of 2 -D shapes You should know the following formulae: h Area

• To succeed at this lesson today you need to… • 1. Break

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We are Learning to…… Calculate Area of Composite Shapes

Area of shapes made from rectangles How can we find the area of this shape? We can think of this shape as being made up of two rectangles. 7 m A Either like this … 10 m 15 m … or like this. 8 m B 15 m Label the rectangles A and B. 5 m Area A = 10 × 7 = 70 m 2 Area B = 5 × 15 = 75 m 2 Total area = 70 + 75 = 145 m 2

Area of shapes made from rectangles How can we find the area of the shaded shape? 7 cm A 8 cm 4 cm 3 cm B We can think of this shape as being made up of one rectangle cut of another rectangle. Label the rectangles A and B. Area A = 7 × 8 = 56 cm 2 Area B = 3 × 4 = 12 cm 2 Total area = 56 – 12 = 44 cm 2

Area of an irregular shape on a pegboard How can we find the area of this irregular quadrilateral constructed on a pegboard? A D E C B We can divide the shape into right-angled triangles and a square. Area A = ½ × 2 × 3 = 3 units 2 Area B = ½ × 2 × 4 = 4 units 2 Area C = ½ × 1 × 3 = 1. 5 units 2 Area D = ½ × 1 × 2 = 1 unit 2 Area E = 1 unit 2 Total shaded area = 10. 5 units 2

Area of an irregular shapes on a pegboard How can we find the area of this irregular quadrilateral constructed on a pegboard? A D B C An alternative method would be to construct a rectangle that passes through each of the vertices. The area of this rectangle is 4 × 5 = 20 units 2 The area of the irregular quadrilateral is found by subtracting the area of each of these triangles.

Area of an irregular shapes on a pegboard How can we find the area of this irregular quadrilateral constructed on a pegboard? A C B D Area A = ½ × 2 × 3 = 3 units 2 Area B = ½ × 2 × 4 = 4 units 2 Area C = ½ × 1 × 2 = 1 units 2 Area D = ½ × 1 × 3 = 1. 5 units 2 Total shaded area = 9. 5 units 2 Area of irregular quadrilateral = (20 – 9. 5) units 2 = 10. 5 units 2

Area formulae of 2 -D shapes You should know the following formulae: h Area of a triangle = bxh 2 b h Area of a parallelogram = b x h b w l Area of a rectangle = l x w

• To succeed at this lesson today you need to… • 1. Break the shape into either rectangles and/or triangles • 2. Work out the area of each part • 3. Find the total Complete Handouts 4. 2. 1 and 4. 2. 2