RD Sharma Chapter 18 Class 9 Maths Exercise 18.2 Solutions can be comprehensive for a greater exercise on surface area and exercises related to Cuboid volume. This exercise is considered the most effective method. This is because of the strategic and stepwise approach to solving the questions.
It can also help the students obtain a broader understanding of different topics around the surface area and problems related to the Cuboid and answer questions on Cubes. To be specific about this exercise, it is more focused on the cuboid volume calculations and exercises around cubes.
Learn about Class 9 Chapter 18 (Surface Area And Volume Of A Cuboid And Cube)
Download RD Sharma Chapter 18 Class 9 Maths Exercise 18.2 Solutions PDF
Solutions for Class 9 Maths Chapter 18 Surface Area and Volume of Cuboid and Cube Exercise 18.2
What are the Topics Covered Under RD Sharma Chapter 18 Class 9 Maths Exercise 18.2 Solutions?
Students are primarily taught about the following topics as part of Class 9 Maths Chapter 18 Cube Exercise 18.2.
- It provides exercises around the surface area of a Cuboid
- It covers the topic around the calculation of the surface area of a cube
- It covers the topics around calculations of lateral surface Area of a Cuboid
- It covers the topics around the Lateral Surface Area of a Cub
Surface Area of a Cuboid
Cuboid comes with six rectangular faces, the surface area of which is calculated upon adding the areas of all six faces. It can be calculated using the formula SA= 2lw+2lh+2hw, where l means length, w means width, and h means the prism’s height.
Surface Area of a Cube
The surface area is calculated through formula A=6a2, where A is the area, and ‘a’ is the length of the edge.
Lateral Surface Area of a Cuboid
The lateral surface area of Cuboid has calculated through the formula Lateral Surface area = 2 height (length + breadth)
Lateral Surface Area of a Cube
The lateral surface area is calculated through formula 4a2, where ‘a’ is the length of each side.
Important Definitions RD Sharma Chapter 18 Class 9 Maths Exercise 18.2 Solutions
Surface Area of a Cuboid
Cuboid comes with six rectangular faces, the surface area of which is calculated upon adding the areas of all six faces. It can be calculated using the formula SA= 2lw+2lh+2hw, where l means length, w means width, and h means the prism’s height.
Surface Area of a Cube
The surface area is calculated through formula A = 6a2, where A is the area, and ‘a’ is the length of the edge.
Lateral Surface Area of a Cuboid
The lateral surface area of Cuboid has calculated through the formula Lateral Surface area = 2 height (length + breadth)
Lateral Surface Area of a Cube
The lateral surface area is calculated through formula 4a2, where ‘a’ is the length of each side.
Examples of RD Sharma Chapter 18 Class 9 Maths Exercise 18.2 Solutions
Ques: A cuboidal water tank measures 5 meters long, 6 meters wide, and 4.5 meters deep. How many liters (l) of water can it hold?
Solution:
Dimensions of the cuboidal tank-
= Length = l = 5m
= Breadth = b = 6m
= Height = h = 4.5m
= Volume of the cuboidal water tank = l x b x h
By equating the values, we get-
= Volume, V = 5× 6× 4.5
= 135
Therefore, Volume of the cuboidal water tank is 135 m3
Converting into liters:
= As 1 m3 = 1000 liters
= So, 135m3 = (135 × 1000) liters
= 135000 liters
Hence, the tank can accommodate 1,35,000 liters of water.
Ques: A cuboidal vessel is 10 meters long and 8 meters wide. How high must it be created to hold 380 cubic meters of a liquid?
Solution:
Dimensions of the cuboidal vessel:
Length = l = 10 m
Breadth = b = 8 m
vessel volume = 380 m3
Let ‘h’ be the height of cuboidal vessel.
Volume of cuboidal vessel = lbh
lbh = 380 m3
or 10× 8× h = 380
or h = (380)/ (10×8)
or h = 4.75
Hence, height of the vessel should be 4.75 m.
Ques: Find the cost of digging a cuboidal hole 8 meters long, 6 meters broad, and 3 meters deep at the rate of Rs 30 per m3.
Solution:
Dimensions of the cuboidal hole-
= Length = l = 8 m
= Breadth = b = 6 m
= Height or depth = h = 3 m
= Volume of the Cuboidal pit = l x b x h
= 8× 6× 3
= 144m3
Volume of the Cuboidal hole is 144 m3
Now, finding the cost-
= Cost of digging 1 m3 hole = Rs. 30 (from question)
= Cost of digging 144 m3 holeit = 144 x 30 = Rs. 4320