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# 2 d shapes

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### 2 d shapes

1. 1. Learning Outcomes Find the perimeter of 2-D composite shape of two or more quadrilaterals and triangles.2. Find the area of a 2-D composite shape of two or more quadrilaterals and triangles.3. Solve problems in real context involving calculation of perimeter and area of 2-D shapes
2. 2. Revision for 2 Dimensional Shapes A perimeter is the total length of the outer sides of a shape Area is the size of a flat surface 8 cm × 3 cm = 24cm² Formula : Area = length x breadth Unit of area : square centimetre (cm²) and square metre ( m²) Area of triangle : Base × Height4 cm height 2 base 3 cm
3. 3. Find the perimeter of 2-D composite shape of two or morequadrilaterals and triangles. Example 1 : 8 cm 10 cm 6 cm Diagram 1 Find the perimeter, in cm, of the above diagram. Recognize all the 10 given lengths of certain sides 8 cm 10 cm Step 1 : 6 cm 10 Total all the Step 2 : distance 10 + 10 + 10 + 8 + 6 = around the diagram = 44 cm REMEMBER ….. A perimeter is the total length of the outer sides of the shape
4. 4. Find the area of a 2-D composite shape of two or morequadrilaterals and triangles. Example 1 8 cm 10 cm 6 cm Diagram 3 Diagram 3 shows a square and rectangle. Find the area, in cm², of the whole diagram. Recognize the length and dimension of the given shape Height 8 cm 10 cm A Step 1 : B Breadth Length 6 cm Base Square = Step 2 : Length × Breadth A = 10 × 10 = 100 cm². Triangle = Base × Height B = 6 × 10 ÷ 2 = 30 cm². 2 Step 3 : Area of the diagram =A+B = 100 cm² + 30 cm² Total up = 130 cm². Example 1 8 cm Diagram 3 Diagram 3 shows a two equal triangles and a square. Find the perimeter, in cm of the whole diagram.
5. 5. 10 cm 6 cm Step 1 :Understanding the problem • To find the perimeter of the diagram. • Given the lengths of certain sides Devise a planStep 2 : using formula • Label the whole diagram for calculatingPerimeter = total distance perimeteroutside edge around thediagram Carry out Step 3 : the plan Perimeter = (10 + 8 + 10 + 6 + 8 + 6) cm = 48 cm. Checking theStep 4 : solution Make sure the calculation is correct. Add only all the outside edges of the diagram.
6. 6. Example 2 6 cm 4 cm The diagram shows a two equal square and a right angled triangle. Find the area, in cm², of the whole diagram. Step 1 : Understanding the problem To find the area of the diagram. The side of the square = 4 cm The based of the triangle = 8 cm Devise a plan Step 2 : using formula for calculating Area of square = length × breadth area Area of triangle = base × height 2 Step 3 : Carry out Area of square = (4 × 4) × 2 = 32 cm² the plan Area of triangle = 8 × 6 ÷ 2 = 24 cm² Total area = 32 cm² + 24 cm² = 56 cm² Checking the Step 4 : solution Make sure the calculation is correct.