Monday, 9 December 2019

Perimeter and Area (Practice Set 47)


Total surface area of a cuboid
=2(lb + bh +lh)


Total surface area of a cube

= 6 X l2.

Practice Set 47
1) Find the total surface area of cubes having the following sides.

i) 3 cm
The total surface area of a cube= 6 X (l2)
                                             = 6 X 3 X3
                                       = 54 cm2.

ii) 5 cm
The total surface area of a cube= 6 X (l2)
                                       = 6 X 5 X 5
                                       = 150 cm2.

iii) 7.2 cm
The total surface area of a cube= 6 X (l2)
                                       = 6 X 7.2 X 7.2
                                    = 311.04 cm2.

iv) 6.8 m
The total surface area of a cube= 6 X (l2)
                               = 6 X 6.8 X 6.8
                               = 277.44m2.

v) 5.5 cm
The total surface area of a cube= 6 X (l2)
                                = 6 X 5.5 X 5.5
                               = 181.5 m2.


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