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NOTES CODE: MT160081ES
In this tutorial, we shall see how areas of shaded parts are obtained by using different techniques. Remember, before you learn this, you have to acquire the good knowledge of how to identify the polygons involved in a question of finding the area of shaded part and to have the knowledge of finding areas of different shapes. Sometimes, shaded part can be a defined polygon or cannot be a defined polygon (odd shape) as the pictures below:
If the shaded part is a defined shape, identify the dimensions and find the area of the defined shape.
Find the area of the shaded part below:
The shaded part is a circle with radius 7m, so your task is only to find the area of that circle, ignore the triangle. Area = πr Therefore the area of the shaded part =
Find the area of the shaded part below:
The shaded part is a square with diagonal 10m, so your task is only to find the area of that square, ignore the circle.
The area of the square by using diagonal is given by: Area = (d x d)/2 or ½ of the square of diagonal Area = (10m x 10m) /2 = 100m Therefore the area of the shaded part =
Find the area of the shaded part below:
The shaded part is a semi-circle with diameter 14cm, so find the area of the semi-circle, and ignore the rectangle. You have to note that, the length of the rectangle is equal to the Diameter of the semi-circle:- Area = Therefore: Area = ½ x Therefore the area of the shaded part =
Sometimes the shaded part cannot be defined i.e. odd shape, you can’t define it whether it is a rectangle, square, trapezium or any defined shape by its name. These questions nearly always involve subtraction. Usually, all you have to do is subtract the white area from the area of the whole figure. So in this condition you need to follow the following steps: Find the area of the whole polygon then find the area of the white polygon then use: (The area of the whole shape) – (the area of the white shape) = the area of the shaded part
Find the area of the shaded part below:
The shaded part is the odd shape, so follow the steps below: (i) Find the area of the rectangle = 14cm x 20cm = 280cm (ii) Find the area of the semi-circle = 77 cm (iii) Take 280cm Therefore the area of the shaded part =
Find the area of the shaded part below:
The shaded part is the odd shape, so follow the steps below: The whole shape is a circle with radius 10 cm The white area inside is a triangle with the following dimensions (i) Base = Diameter of the circle = 20 cm (ii) Height = Radius of the circle = 10 cm Therefore find the areas of the polygons as follows: (i) The area of the circle = PI x r x r = 3.14 x 10cm x 10cm = 314cm (ii) The area of the triangle = ½ x Base x height = ½ x 20cm x 10cm = 100cm To get the shaded part take the area of the whole polygon, this is the circle minus the area of the triangle: Then, 314cm Therefore the area of the shaded part =
Find the areas of the shaded parts below:
************** END ******************In case of any question or comment be free to write down:A lot of Thanks Mr. Yahya M (Badshah) ****** MT160081ES ******* | |

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