24 Area Subunit Area of Rectangles Area of

24. Area Subunit : Area of Rectangles Area of square

Definition of a Rectangle n A rectangle is a quadrilateral with opposite sides that are equal and parallel and with four right angles.

Definition of Area n n n Area The measure of place occupied on a flat surface is called Area of the figure. units sq. cm or cm 2 (square centimeter) n sq. m or m 2 (square meter)

What are length and breadth? n In order to calculate the area of a rectangle, you need to know the length and width of the rectangle. n n Length (l) is the measure of one side of the rectangle. Breadth (b) is the measure of an adjacent side of the rectangle. Breadth(b)

Finding Area n n n This rectangle is has a length of 6 units and a width of 3 units. To find the area of this rectangle count the number of squares (units). The area of this rectangle is 18 units.

Calculating Area n n You may not always have a rectangle with squares (units) inside of it, so you need a formula. The formula for calculating the area of a rectangle is A = l x b. A is area n l is length n b is breadth n Breadth(b)

Example n n Let’s do an example problem. What are the dimensions of the red rectangle? l = 10 cm n b = 3 cm n n A=lxb A = 10 cm x 3 cm 2 n A = 30 cm n n The area of the red rectangle is 30 cm 2.

Practice! 17 m Rectangle 10 m A=lxb A = 17 m x 10 m A = 170 sq. m

A Real Life Example n Suresh is putting carpet in a bedroom that measures 14 ft by 12 ft. How many square feet of carpet does Suresh need? n What do you know? n The dimensions of the room is 14 ft by 12 ft. n n n A=lxb n n n l = 14 ft b = 12 ft A = 14 ft x 12 ft A = 168 ft 2 Suresh needs 168 ft 2 of carpet.

24. Area Subunit : Area of square

Definition of Area n n n Area The measure of place occupied on a flat surface is called Area of the figure. units sq. cm or cm 2 (square centimeter) n sq. m or m 2 (square meter)

Calculating Area n n n Area of square = side × side =x×x = x 2 A is area n x is length of side n

Example n n n Let’s do an example problem. 1 What is the area of this square? Solution Area =x 2 = x × x = 3. 2 × 3. 2 = 10. 24 cm 2

Practice! 17 m Rectangle 17 m Area =x 2 = x × x = 17 × 17 = 289 cm 2

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