• Perimeter of a closed figure is the distance around it while area is

the measure of the part of plane or region enclosed by it.

• Perimeter of a regular polygon = Number of sides × Length of one

side.

• Perimeter of a square = 4 × side

Fig. 9.1

• Perimeter of a rectangle = 2(l + b)

Fig. 9.2

• Area of square = side × side

• Area of rectangle = l × b

• Area of parallelogram = b × h

• Area of triangle =

1

2

×b×h

Fig. 9.3

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Fig. 9.4

• The distance around a circle is known as its circumference.

• The ratio of circumference and diameter of a circle is a constant and

is denoted by π (pi).

• Approximate value of π is taken as 22

7

or 3.14

• Circumference of a circle of radius r is 2πr,

• Area of a circle of radius r is πr2.

Fig. 9.5

In Examples 1 and 2, there are four options, out of which one is correct.

Choose the correct one.

Example 1: Following rectangle is composed of 8 congruent parts.

Fig. 9.6



Words Numbers Formula

The circumference C of

a circle is π times the

diameter d, or 2π

times the radius r.

C = π × 6

= 2π × 3

= 18.8 units

C = πd

or

C = 2πr

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Area of each part is

(a) 72 cm2 (b) 36 cm2 (c) 18 cm2 (d) 9 cm2

Solution: Correct answer is (d).

Example 2: Area of a right triangle is 54 cm2. If one of its legs is

12 cm long, its perimeter is

(a) 18 cm (b) 27 cm (c) 36 cm (d) 54 cm

Answer:

9. B

10. B

Step-by-step explanation:

para po makuha Yung sagot sa perimeters add lang po Lahat ng sides

To find the perimeter of a rectangle or square you have to add the lengths of all the four sides