Calculate The Area of Composite 2-D Shapes

The area of a composite 2-D shape can be found by finding the areas of individual shape and adding them up.

 Example :

     

     

                                                             

                                                 

                                Area = Length x Breadth       

                           

                                 

You can learn more about area of rectangle by clicking             this powerpoint presentation :  Area_of_rectangles_JB.ppt       

                Tired of learning? Play some games here, have fun!

                                             Perimeter and Area Games              

            

  

Area of Composite 2-D Shapes

Area is the amount of space contained inside a 2D shape.

If the shape is drawn accurately on squared paper, you

just need to count the amount of squares that are 

contained inside the shape. Simple as ABC, right?

Examples :

  

      

                                                         

Let's practise

Can you find the area of the composite shape below?

                                                                      2
Answer = (3x7) + ( 2x3) + (3x6)= 45cm


            Here is an interesting video clip to be watched, do enjoy it!        

Solve problems involving perimeters of composite 2-D shapes

Let's practise

 

1. Mei Eng  made a bookmark using a rectangle and a triangle. Find the perimeter of the bookmark.

 2. Can you find the perimeter  of the road signboard to your school? It was a composite shape of rectangle and a triangle.

                                       

3. Find the perimeter of this letter

      "T ". 

 

********************************************************************************************************************                                    1. (5 + 5 + 17 + 4 +17 ) cm = 48cm

 
          2. ( 42 + 3 + 12 + 12 + 3 + 42 + 8 ) cm = 122 cm 

  3. ( 10 + 2 + 4 + 12 + 2 + 12 + 4 + 2 ) cm = 48 cm

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                    You can work out some exercises from the website given: 

                  Quiz engine for perimeter                                                          

Treat yourself by making a bookmark.

Perimeter of Composite 2-D Shapes

To find the perimeter of composite 2-D shapes, we have to add up the lengths of all the sides of the joined shapes.

Calculate the perimeter of  the following shapes.

Worked Example 1:

Solution

The composite shape is made up of  a rectangle and a triangle.     

Perimeter = the total length of its sides

                 = ( 6 + 6 + 2 + 4 + 8 + 4 ) cm

                 = 30 cm

            

 Worked Example 2: 

Solution

The composite shape is made up of  a square and a triangle.     


Perimeter = the total length of its sides
                 = ( 4 + 4 + 4 + 4 + 8 + 8 ) cm
                 =   32 cm

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                          So children, time to sing a song.

                          Do enjoy yourself and have fun.

                                    Perimeter Song

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