### Mathematics Class VII

Integers
Fractions and Decimals
Exponents and Powers
Algebraic Equations
Simple Linear Equations
Lines and Angles
Comparing Quantities
Congruence of Triangles
Rational Numbers
Perimeter and Area
Data Handling
Practical Geometry
Symmetry
Visualising Solid Shapes

# Conversion Of Units

Sometimes we need to convert the unit of the given measurements to make it similar to the other given units.

Example: 1

Convert 70 cmin mm2

Solution:

1 cm = 10 mm

1 cm= 10 × 10

1 cm= 100 mm2

70 cm= 700 mm2

Example: 2

Convert 3.5 ha in m2

Solution:

1 ha = 10000 m2

3.5 ha = 10000 × 3.5

ha = 35000 m2

##### Applications

We can use these concepts of area and perimeter of plane figures in our day to day life.

• If we have a rectangular field and want to calculate that how long will be the length of the fence required to cover that field, then we will use the perimeter.
• If a child has to decorate a circular card with the lace then he can calculate the length of the lace required by calculating the circumference of the card, etc.

Example:

A rectangular park is 35 m long and 20 m wide. A path 1.5 m wide is constructed outside the park. Find the area of the path.

Solution

Area of rectangle ABCD – Area of rectangle STUV

AB = 35 + 2.5 + 2.5

= 40 m

AD = 20 + 2.5 + 2.5

= 25 m

Area of ABCD = 40 × 25

= 1000 m2

Area of STUV = 35 × 20

= 700 m2

Area of path = Area of rectangle ABCD – Area of rectangle STUV

= 1000 – 700

= 300 m2

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